Network compatibility changes

94 files changed, 1008 insertions, 743 deletions

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..60097c8
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,231 @@
+name: Build
+
+on:
+  workflow_dispatch:
+
+  pull_request:
+    branches:
+      - "*"
+
+jobs:
+  build_windows:
+    name: Build OpenStarbound Windows x64
+    runs-on: windows-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+
+      - name: Install CMake & Ninja
+        uses: lukka/get-cmake@latest
+        with:
+          cmakeVersion: 3.29.2
+
+      - name: sccache
+        uses: hendrikmuhs/ccache-action@v1.2
+        with:
+          variant: sccache
+          key: ${{ github.job }}-${{ runner.os }}
+          max-size: 1000M
+
+      - uses: ilammy/msvc-dev-cmd@v1
+
+      - name: vcpkg
+        uses: lukka/run-vcpkg@v11
+        id: runvcpkg
+        with:
+          vcpkgJsonGlob: '**/source/vcpkg.json'
+          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
+
+      - name: Run CMake
+        uses: lukka/run-cmake@v10
+        with:
+          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
+          configurePreset: 'windows-release'
+          buildPreset: 'windows-release'
+          testPreset: 'windows-release'
+
+      - name: Run Post-Build Task
+        working-directory: ${{ github.workspace }}
+        run: scripts\ci\windows\post_build.bat
+
+      - name: Assemble Files
+        working-directory: ${{ github.workspace }}
+        run: scripts\ci\windows\assemble.bat
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Windows-All-DevOnly
+          path: dist/*
+
+      - name: Upload Client
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Windows-Client
+          path: client_distribution/*
+
+      - name: Upload Server
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Windows-Server
+          path: server_distribution/*
+
+      - name: Create Installer
+        working-directory: ${{ github.workspace }}
+        run: |
+          & "C:\Program Files (x86)\Inno Setup 6\iscc.exe" /Oinstaller scripts\inno\setup.iss
+
+      - name: Upload Installer
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Windows-Installer
+          path: installer/*
+  
+  build_linux:
+    name: Build OpenStarbound Linux x86_64
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Install Packages
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y pkg-config libxmu-dev libxi-dev libgl-dev libglu1-mesa-dev libsdl2-dev
+
+      - name: Install CMake & Ninja
+        uses: lukka/get-cmake@latest
+        with:
+          cmakeVersion: 3.29.2
+
+      - uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+
+      - name: sccache
+        uses: hendrikmuhs/ccache-action@v1.2
+        with:
+          variant: sccache
+          key: ${{ github.job }}-${{ runner.os }}
+          max-size: 250M
+
+      - name: vcpkg
+        uses: lukka/run-vcpkg@v11
+        id: runvcpkg
+        with:
+          vcpkgJsonGlob: '**/source/vcpkg.json'
+          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
+
+      - name: Run CMake
+        uses: lukka/run-cmake@v10
+        with:
+          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
+          configurePreset: 'linux-release'
+          buildPreset: 'linux-release'
+          testPreset: 'linux-release'
+
+      - name: Assemble Files
+        working-directory: ${{ github.workspace }}
+        run: scripts/ci/linux/assemble.sh
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Linux
+          path: dist.tar
+
+      - name: Upload Client Files
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Linux-Client
+          path: client.tar
+
+      - name: Upload Server Files
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-Linux-Server
+          path: server.tar
+
+  build-mac-intel:
+    name: Build OpenStarbound macOS x86_64
+    runs-on: macos-13
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+
+      - name: Install CMake & Ninja
+        uses: lukka/get-cmake@latest
+        with:
+          cmakeVersion: 3.29.0
+
+      - name: sccache
+        uses: hendrikmuhs/ccache-action@v1.2
+        with:
+          variant: sccache
+          key: ${{ github.job }}-Intel-${{ runner.os }}
+          max-size: 250M
+
+      - name: vcpkg
+        uses: lukka/run-vcpkg@v11
+        id: runvcpkg
+        with:
+          vcpkgJsonGlob: '**/source/vcpkg.json'
+          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
+
+      - name: Run CMake
+        uses: lukka/run-cmake@v10
+        with:
+          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
+          configurePreset: 'macos-release'
+          buildPreset: 'macos-release'
+          testPreset: 'macos-release'
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-macOS-Intel
+          path: dist/*
+
+  build-mac-arm:
+    name: Build OpenStarbound macOS arm64
+    runs-on: macos-14
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: 'recursive'
+
+      - name: Install CMake & Ninja
+        uses: lukka/get-cmake@latest
+        with:
+          cmakeVersion: 3.29.2
+
+      - name: sccache
+        uses: hendrikmuhs/ccache-action@v1.2
+        with:
+          variant: sccache
+          key: ${{ github.job }}-ARM-${{ runner.os }}
+          max-size: 250M
+
+      - name: vcpkg
+        uses: lukka/run-vcpkg@v11
+        id: runvcpkg
+        with:
+          vcpkgJsonGlob: '**/source/vcpkg.json'
+          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
+
+      - name: Run CMake
+        uses: lukka/run-cmake@v10
+        with:
+          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
+          configurePreset: 'macos-arm-release'
+          buildPreset: 'macos-arm-release'
+          testPreset: 'macos-arm-release'
+
+      - name: Upload Artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: OpenStarbound-macOS-Silicon
+          path: dist/*
\ No newline at end of file
diff --git a/.github/workflows/build_linux.yml b/.github/workflows/build_linux.yml
deleted file mode 100644
index 307b30f..0000000
--- a/.github/workflows/build_linux.yml
+++ /dev/null
@@ -1,76 +0,0 @@
-name: Ubuntu Linux
-
-on:
-  push:
-    branches:
-      - "*"
-    tags:
-      - "*"
-
-  pull_request:
-    branches:
-      - "*"
-
-jobs:
-  build:
-    name: OpenStarbound Linux x86_64
-    runs-on: ubuntu-20.04
-
-    steps:
-      - name: Install Packages
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y pkg-config libxmu-dev libxi-dev libgl-dev libglu1-mesa-dev libsdl2-dev
-
-      - name: Install CMake & Ninja
-        uses: lukka/get-cmake@latest
-        with:
-          cmakeVersion: 3.29.2
-
-      - uses: actions/checkout@v4
-        with:
-          submodules: 'recursive'
-
-      - name: sccache
-        uses: hendrikmuhs/ccache-action@v1.2
-        with:
-          variant: sccache
-          key: ${{ github.job }}-${{ runner.os }}
-          max-size: 250M
-
-      - name: vcpkg
-        uses: lukka/run-vcpkg@v11
-        id: runvcpkg
-        with:
-          vcpkgJsonGlob: '**/source/vcpkg.json'
-          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
-
-      - name: Run CMake
-        uses: lukka/run-cmake@v10
-        with:
-          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
-          configurePreset: 'linux-release'
-          buildPreset: 'linux-release'
-          testPreset: 'linux-release'
-
-      - name: Assemble Files
-        working-directory: ${{ github.workspace }}
-        run: scripts/ci/linux/assemble.sh
-
-      - name: Upload Artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Linux
-          path: dist.tar
-
-      - name: Upload Client Files
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Linux-Client
-          path: client.tar
-
-      - name: Upload Server Files
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Linux-Server
-          path: server.tar
\ No newline at end of file
diff --git a/.github/workflows/build_macos.yml b/.github/workflows/build_macos.yml
deleted file mode 100644
index 1cfd12c..0000000
--- a/.github/workflows/build_macos.yml
+++ /dev/null
@@ -1,97 +0,0 @@
-name: macOS
-
-on:
-  push:
-    branches:
-      - "*"
-    tags:
-      - "*"
-
-  pull_request:
-    branches:
-      - "*"
-
-jobs:
-  build-intel:
-    name: OpenStarbound macOS x86_64
-    runs-on: macos-13
-
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          submodules: 'recursive'
-
-      - name: Install CMake & Ninja
-        uses: lukka/get-cmake@latest
-        with:
-          cmakeVersion: 3.29.0
-
-      - name: sccache
-        uses: hendrikmuhs/ccache-action@v1.2
-        with:
-          variant: sccache
-          key: ${{ github.job }}-Intel-${{ runner.os }}
-          max-size: 250M
-
-      - name: vcpkg
-        uses: lukka/run-vcpkg@v11
-        id: runvcpkg
-        with:
-          vcpkgJsonGlob: '**/source/vcpkg.json'
-          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
-
-      - name: Run CMake
-        uses: lukka/run-cmake@v10
-        with:
-          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
-          configurePreset: 'macos-release'
-          buildPreset: 'macos-release'
-          testPreset: 'macos-release'
-
-      - name: Upload Artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-macOS-Intel
-          path: dist/*
-
-  build-arm:
-    name: OpenStarbound macOS arm64
-    runs-on: macos-14
-
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          submodules: 'recursive'
-
-      - name: Install CMake & Ninja
-        uses: lukka/get-cmake@latest
-        with:
-          cmakeVersion: 3.29.2
-
-      - name: sccache
-        uses: hendrikmuhs/ccache-action@v1.2
-        with:
-          variant: sccache
-          key: ${{ github.job }}-ARM-${{ runner.os }}
-          max-size: 250M
-
-      - name: vcpkg
-        uses: lukka/run-vcpkg@v11
-        id: runvcpkg
-        with:
-          vcpkgJsonGlob: '**/source/vcpkg.json'
-          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
-
-      - name: Run CMake
-        uses: lukka/run-cmake@v10
-        with:
-          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
-          configurePreset: 'macos-arm-release'
-          buildPreset: 'macos-arm-release'
-          testPreset: 'macos-arm-release'
-
-      - name: Upload Artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-macOS-Silicon
-          path: dist/*
\ No newline at end of file
diff --git a/.github/workflows/build_windows.yml b/.github/workflows/build_windows.yml
deleted file mode 100644
index d3ee36b..0000000
--- a/.github/workflows/build_windows.yml
+++ /dev/null
@@ -1,89 +0,0 @@
-name: Windows
-
-on:
-  push:
-    branches:
-      - "*"
-    tags:
-      - "*"
-
-  pull_request:
-    branches:
-      - "*"
-
-jobs:
-  build:
-    name: Build OpenStarbound Windows x64
-    runs-on: windows-latest
-
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-        with:
-          submodules: 'recursive'
-
-      - name: Install CMake & Ninja
-        uses: lukka/get-cmake@latest
-        with:
-          cmakeVersion: 3.29.2
-
-      - name: sccache
-        uses: hendrikmuhs/ccache-action@v1.2
-        with:
-          variant: sccache
-          key: ${{ github.job }}-${{ runner.os }}
-          max-size: 1000M
-
-      - uses: ilammy/msvc-dev-cmd@v1
-
-      - name: vcpkg
-        uses: lukka/run-vcpkg@v11
-        id: runvcpkg
-        with:
-          vcpkgJsonGlob: '**/source/vcpkg.json'
-          vcpkgConfigurationJsonGlob: '**/source/vcpkg-configuration.json'
-
-      - name: Run CMake
-        uses: lukka/run-cmake@v10
-        with:
-          cmakeListsTxtPath: '${{ github.workspace }}/source/CMakeLists.txt'
-          configurePreset: 'windows-release'
-          buildPreset: 'windows-release'
-          testPreset: 'windows-release'
-
-      - name: Run Post-Build Task
-        working-directory: ${{ github.workspace }}
-        run: scripts\ci\windows\post_build.bat
-
-      - name: Assemble Files
-        working-directory: ${{ github.workspace }}
-        run: scripts\ci\windows\assemble.bat
-
-      - name: Upload Artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Windows-All-DevOnly
-          path: dist/*
-
-      - name: Upload Client
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Windows-Client
-          path: client_distribution/*
-
-      - name: Upload Server
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Windows-Server
-          path: server_distribution/*
-
-      - name: Create Installer
-        working-directory: ${{ github.workspace }}
-        run: |
-          & "C:\Program Files (x86)\Inno Setup 6\iscc.exe" /Oinstaller scripts\inno\setup.iss
-
-      - name: Upload Installer
-        uses: actions/upload-artifact@v4
-        with:
-          name: OpenStarbound-Windows-Installer
-          path: installer/*
diff --git a/source/base/StarAssets.cpp b/source/base/StarAssets.cpp
index c47b71c..f81a4ee 100644
--- a/source/base/StarAssets.cpp
+++ b/source/base/StarAssets.cpp
@@ -68,7 +68,7 @@ static void validatePath(AssetPath const& components, bool canContainSubPath, bo
     throw AssetException::format("Path '{}' cannot contain directives", components);
 }
 
-static void validatePath(StringView const& path, bool canContainSubPath, bool canContainDirectives) {
+static void validatePath(StringView path, bool canContainSubPath, bool canContainDirectives) {
   std::string_view const& str = path.utf8();
 
   size_t end = str.find_first_of(":?");
diff --git a/source/core/CMakeLists.txt b/source/core/CMakeLists.txt
index fb31fca..bb8bd22 100644
--- a/source/core/CMakeLists.txt
+++ b/source/core/CMakeLists.txt
@@ -70,10 +70,12 @@ SET (star_core_HEADERS
     StarMultiArray.hpp
     StarMultiArrayInterpolator.hpp
     StarMultiTable.hpp
+    StarNetCompatibility.hpp
     StarNetElement.hpp
     StarNetElementBasicFields.hpp
     StarNetElementContainers.hpp
     StarNetElementDynamicGroup.hpp
+    StarNetElementExt.hpp
     StarNetElementFloatFields.hpp
     StarNetElementGroup.hpp
     StarNetElementSignal.hpp
diff --git a/source/core/StarDataStream.cpp b/source/core/StarDataStream.cpp
index 18456b6..1224f54 100644
--- a/source/core/StarDataStream.cpp
+++ b/source/core/StarDataStream.cpp
@@ -35,6 +35,13 @@ void DataStream::setStreamCompatibilityVersion(unsigned streamCompatibilityVersi
   m_streamCompatibilityVersion = streamCompatibilityVersion;
 }
 
+void DataStream::setStreamCompatibilityVersion(NetCompatibilityRules const& rules) {
+  if (rules.isLegacy)
+    m_streamCompatibilityVersion = 1;
+  else
+    m_streamCompatibilityVersion = CurrentStreamVersion;
+}
+
 ByteArray DataStream::readBytes(size_t len) {
   ByteArray ba;
   ba.resize(len);
diff --git a/source/core/StarDataStream.hpp b/source/core/StarDataStream.hpp
index 02cb922..abcbff4 100644
--- a/source/core/StarDataStream.hpp
+++ b/source/core/StarDataStream.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "StarString.hpp"
+#include "StarNetCompatibility.hpp"
 
 namespace Star {
 
@@ -12,7 +13,7 @@ public:
   DataStream();
   virtual ~DataStream() = default;
 
-  static unsigned const CurrentStreamVersion = 1;
+  static unsigned const CurrentStreamVersion = 2;
 
   // DataStream defaults to big-endian order for all primitive types
   ByteOrder byteOrder() const;
@@ -27,7 +28,7 @@ public:
   // changed for compatibility with older versions of DataStream serialization.
   unsigned streamCompatibilityVersion() const;
   void setStreamCompatibilityVersion(unsigned streamCompatibilityVersion);
-
+  void setStreamCompatibilityVersion(NetCompatibilityRules const& rules);
   // Do direct reads and writes
   virtual void readData(char* data, size_t len) = 0;
   virtual void writeData(char const* data, size_t len) = 0;
diff --git a/source/core/StarDataStreamDevices.hpp b/source/core/StarDataStreamDevices.hpp
index 3f34a72..4452592 100644
--- a/source/core/StarDataStreamDevices.hpp
+++ b/source/core/StarDataStreamDevices.hpp
@@ -126,8 +126,8 @@ private:
 class DataStreamExternalBuffer : public DataStream {
 public:
   DataStreamExternalBuffer();
-  explicit DataStreamExternalBuffer(ByteArray const& byteArray);
-  explicit DataStreamExternalBuffer(DataStreamBuffer const& buffer);
+  DataStreamExternalBuffer(ByteArray const& byteArray);
+  DataStreamExternalBuffer(DataStreamBuffer const& buffer);
 
   DataStreamExternalBuffer(DataStreamExternalBuffer const& buffer) = default;
   DataStreamExternalBuffer(char const* externalData, size_t len);
diff --git a/source/core/StarNetCompatibility.hpp b/source/core/StarNetCompatibility.hpp
new file mode 100644
index 0000000..730546e
--- /dev/null
+++ b/source/core/StarNetCompatibility.hpp
@@ -0,0 +1,41 @@
+#pragma once
+#include "StarDataStream.hpp"
+
+namespace Star {
+
+
+enum class NetCompatibilityFilter {
+  None = 0,
+  Old = 1,
+  New = 2
+};
+
+struct NetCompatibilityRules {
+  NetCompatibilityRules() = default;
+  NetCompatibilityRules(uint64_t) = delete;
+  NetCompatibilityRules(bool legacy);
+
+  bool checkFilter(NetCompatibilityFilter const& filter) const;
+
+  bool isLegacy = false;
+};
+
+inline NetCompatibilityRules::NetCompatibilityRules(bool legacy) : isLegacy(legacy) {}
+
+inline bool NetCompatibilityRules::checkFilter(NetCompatibilityFilter const& filter) const {
+  if (filter == NetCompatibilityFilter::None)
+    return true;
+  else if (isLegacy)
+    return filter == NetCompatibilityFilter::Old;
+  else
+    return filter == NetCompatibilityFilter::New;
+}
+
+template <>
+struct hash<NetCompatibilityRules> {
+  size_t operator()(NetCompatibilityRules const& s) const {
+    return s.isLegacy;
+  }
+};
+
+}
\ No newline at end of file
diff --git a/source/core/StarNetElement.cpp b/source/core/StarNetElement.cpp
index 914badd..343d45a 100644
--- a/source/core/StarNetElement.cpp
+++ b/source/core/StarNetElement.cpp
@@ -7,8 +7,8 @@ uint64_t NetElementVersion::current() const {
   return m_version;
 }
 
-void NetElementVersion::increment() {
-  ++m_version;
+uint64_t NetElementVersion::increment() {
+  return ++m_version;
 }
 
 void NetElement::enableNetInterpolation(float) {}
diff --git a/source/core/StarNetElement.hpp b/source/core/StarNetElement.hpp
index dd909b8..393dd3d 100644
--- a/source/core/StarNetElement.hpp
+++ b/source/core/StarNetElement.hpp
@@ -9,7 +9,7 @@ namespace Star {
 class NetElementVersion {
 public:
   uint64_t current() const;
-  void increment();
+  uint64_t increment();
 
 private:
   uint64_t m_version = 0;
@@ -20,15 +20,15 @@ class NetElement {
 public:
   virtual ~NetElement() = default;
 
-  // A network of NetElements will have a shared monotinically increasing
+  // A network of NetElements will have a shared monotonically increasing
   // NetElementVersion.  When elements are updated, they will mark the version
   // number at the time they are updated so that a delta can be constructed
   // that contains only changes since any past version.
   virtual void initNetVersion(NetElementVersion const* version = nullptr) = 0;
 
   // Full store / load of the entire element.
-  virtual void netStore(DataStream& ds) const = 0;
-  virtual void netLoad(DataStream& ds) = 0;
+  virtual void netStore(DataStream& ds, NetCompatibilityRules rules) const = 0;
+  virtual void netLoad(DataStream& ds, NetCompatibilityRules rules) = 0;
 
   // Enables interpolation mode.  If interpolation mode is enabled, then
   // NetElements will delay presenting incoming delta data for the
@@ -46,14 +46,32 @@ public:
   // the version at the time of the *last* call to writeDelta, + 1.  If
   // fromVersion is 0, this will always write the full state.  Should return
   // true if a delta was needed and was written to DataStream, false otherwise.
-  virtual bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const = 0;
+  virtual bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const = 0;
   // Read a delta written by writeNetDelta.  'interpolationTime' is the time in
   // the future that data from this delta should be delayed and smoothed into,
   // if interpolation is enabled.
-  virtual void readNetDelta(DataStream& ds, float interpolationTime = 0.0) = 0;
+  virtual void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) = 0;
   // When extrapolating, it is important to notify when a delta WOULD have been
   // received even if no deltas are produced, so no extrapolation takes place.
   virtual void blankNetDelta(float interpolationTime);
+
+  NetCompatibilityFilter netCompatibilityFilter() const;
+  void setNetCompatibilityFilter(NetCompatibilityFilter netFilter);
+  bool checkWithRules(NetCompatibilityRules const& rules) const;
+private:
+  NetCompatibilityFilter m_netCompatibilityFilter = NetCompatibilityFilter::None;
 };
 
+inline NetCompatibilityFilter NetElement::netCompatibilityFilter() const {
+  return m_netCompatibilityFilter;
+}
+
+inline void NetElement::setNetCompatibilityFilter(NetCompatibilityFilter netFilter) {
+  m_netCompatibilityFilter = netFilter;
+}
+
+inline bool NetElement::checkWithRules(NetCompatibilityRules const& rules) const {
+  return rules.checkFilter(m_netCompatibilityFilter);
+}
+
 }
diff --git a/source/core/StarNetElementBasicFields.cpp b/source/core/StarNetElementBasicFields.cpp
index bbb5c5b..618c4a6 100644
--- a/source/core/StarNetElementBasicFields.cpp
+++ b/source/core/StarNetElementBasicFields.cpp
@@ -49,8 +49,8 @@ void NetElementEvent::setIgnoreOccurrencesOnNetLoad(bool ignoreOccurrencesOnNetL
   m_ignoreOccurrencesOnNetLoad = ignoreOccurrencesOnNetLoad;
 }
 
-void NetElementEvent::netLoad(DataStream& ds) {
-  NetElementUInt::netLoad(ds);
+void NetElementEvent::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  NetElementUInt::netLoad(ds, rules);
   if (m_ignoreOccurrencesOnNetLoad)
     ignoreOccurrences();
 }
diff --git a/source/core/StarNetElementBasicFields.hpp b/source/core/StarNetElementBasicFields.hpp
index 693c6c3..3b46cc0 100644
--- a/source/core/StarNetElementBasicFields.hpp
+++ b/source/core/StarNetElementBasicFields.hpp
@@ -38,11 +38,11 @@ public:
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
 protected:
   virtual void readData(DataStream& ds, T& t) const = 0;
@@ -107,7 +107,7 @@ public:
   void ignoreOccurrences();
   void setIgnoreOccurrencesOnNetLoad(bool ignoreOccurrencesOnNetLoad);
 
-  void netLoad(DataStream& ds) override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
 protected:
   void updated() override;
@@ -211,7 +211,8 @@ void NetElementBasicField<T>::tickNetInterpolation(float dt) {
 }
 
 template <typename T>
-void NetElementBasicField<T>::netStore(DataStream& ds) const {
+void NetElementBasicField<T>::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   if (m_pendingInterpolatedValues && !m_pendingInterpolatedValues->empty())
     writeData(ds, m_pendingInterpolatedValues->last().second);
   else
@@ -219,7 +220,8 @@ void NetElementBasicField<T>::netStore(DataStream& ds) const {
 }
 
 template <typename T>
-void NetElementBasicField<T>::netLoad(DataStream& ds) {
+void NetElementBasicField<T>::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   readData(ds, m_value);
   m_latestUpdateVersion = m_netVersion ? m_netVersion->current() : 0;
   updated();
@@ -228,7 +230,8 @@ void NetElementBasicField<T>::netLoad(DataStream& ds) {
 }
 
 template <typename T>
-bool NetElementBasicField<T>::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool NetElementBasicField<T>::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   if (m_latestUpdateVersion < fromVersion)
     return false;
 
@@ -236,11 +239,13 @@ bool NetElementBasicField<T>::writeNetDelta(DataStream& ds, uint64_t fromVersion
     writeData(ds, m_pendingInterpolatedValues->last().second);
   else
     writeData(ds, m_value);
+
   return true;
 }
 
 template <typename T>
-void NetElementBasicField<T>::readNetDelta(DataStream& ds, float interpolationTime) {
+void NetElementBasicField<T>::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   T t;
   readData(ds, t);
   m_latestUpdateVersion = m_netVersion ? m_netVersion->current() : 0;
diff --git a/source/core/StarNetElementContainers.hpp b/source/core/StarNetElementContainers.hpp
index 62cce86..2e16b30 100644
--- a/source/core/StarNetElementContainers.hpp
+++ b/source/core/StarNetElementContainers.hpp
@@ -26,11 +26,12 @@ public:
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f) override;
+  bool shouldWriteNetDelta(uint64_t fromVersion, NetCompatibilityRules rules = {}) const;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   mapped_type const& get(key_type const& key) const;
   mapped_type const* ptr(key_type const& key) const;
@@ -77,6 +78,8 @@ public:
   template <typename MapType>
   void setContents(MapType const& values);
 
+  uint64_t changeDataLastVersion() const;
+
 private:
   // If a delta is written from further back than this many steps, the delta
   // will fall back to a full serialization of the entire state.
@@ -152,7 +155,8 @@ void NetElementMapWrapper<BaseMap>::tickNetInterpolation(float dt) {
 }
 
 template <typename BaseMap>
-void NetElementMapWrapper<BaseMap>::netStore(DataStream& ds) const {
+void NetElementMapWrapper<BaseMap>::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   ds.writeVlqU(BaseMap::size() + m_pendingChangeData.size());
   for (auto const& pair : *this)
     writeChange(ds, SetChange{pair.first, pair.second});
@@ -162,7 +166,8 @@ void NetElementMapWrapper<BaseMap>::netStore(DataStream& ds) const {
 }
 
 template <typename BaseMap>
-void NetElementMapWrapper<BaseMap>::netLoad(DataStream& ds) {
+void NetElementMapWrapper<BaseMap>::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   m_changeData.clear();
   m_changeDataLastVersion = m_netVersion ? m_netVersion->current() : 0;
   m_pendingChangeData.clear();
@@ -181,13 +186,27 @@ void NetElementMapWrapper<BaseMap>::netLoad(DataStream& ds) {
 }
 
 template <typename BaseMap>
-bool NetElementMapWrapper<BaseMap>::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool NetElementMapWrapper<BaseMap>::shouldWriteNetDelta(uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
+  if (fromVersion < m_changeDataLastVersion)
+    return true;
+
+  for (auto const& p : m_changeData)
+    if (p.first >= fromVersion)
+      return true;
+
+  return false;
+}
+
+template <typename BaseMap>
+bool NetElementMapWrapper<BaseMap>::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   bool deltaWritten = false;
 
   if (fromVersion < m_changeDataLastVersion) {
     deltaWritten = true;
     ds.writeVlqU(1);
-    netStore(ds);
+    netStore(ds, rules);
 
   } else {
     for (auto const& p : m_changeData) {
@@ -206,13 +225,14 @@ bool NetElementMapWrapper<BaseMap>::writeNetDelta(DataStream& ds, uint64_t fromV
 }
 
 template <typename BaseMap>
-void NetElementMapWrapper<BaseMap>::readNetDelta(DataStream& ds, float interpolationTime) {
+void NetElementMapWrapper<BaseMap>::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   while (true) {
     uint64_t code = ds.readVlqU();
     if (code == 0) {
       break;
     } else if (code == 1) {
-      netLoad(ds);
+      netLoad(ds, rules);
     } else if (code == 2) {
       auto change = readChange(ds);
       addChangeData(change);
@@ -382,6 +402,11 @@ void NetElementMapWrapper<BaseMap>::setContents(MapType const& values) {
 }
 
 template <typename BaseMap>
+uint64_t NetElementMapWrapper<BaseMap>::changeDataLastVersion() const {
+  return m_changeDataLastVersion;
+}
+
+template <typename BaseMap>
 void NetElementMapWrapper<BaseMap>::writeChange(DataStream& ds, ElementChange const& change) {
   if (auto sc = change.template ptr<SetChange>()) {
     ds.write<uint8_t>(0);
diff --git a/source/core/StarNetElementDynamicGroup.hpp b/source/core/StarNetElementDynamicGroup.hpp
index 4f3a2d3..dbd0c12 100644
--- a/source/core/StarNetElementDynamicGroup.hpp
+++ b/source/core/StarNetElementDynamicGroup.hpp
@@ -45,11 +45,11 @@ public:
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
   void blankNetDelta(float interpolationTime = 0.0f) override;
 
 private:
@@ -89,7 +89,7 @@ template <typename Element>
 auto NetElementDynamicGroup<Element>::addNetElement(ElementPtr element) -> ElementId {
   readyElement(element);
   DataStreamBuffer storeBuffer;
-  element->netStore(storeBuffer);
+  element->netStore(storeBuffer, {});
   auto id = m_idMap.add(std::move(element));
 
   addChangeData(ElementAddition(id, storeBuffer.takeData()));
@@ -134,7 +134,7 @@ void NetElementDynamicGroup<Element>::initNetVersion(NetElementVersion const* ve
   for (auto& pair : m_idMap) {
     pair.second->initNetVersion(m_netVersion);
     DataStreamBuffer storeBuffer;
-    pair.second->netStore(storeBuffer);
+    pair.second->netStore(storeBuffer, {});
     addChangeData(ElementAddition(pair.first, storeBuffer.takeData()));
   }
 }
@@ -162,19 +162,22 @@ void NetElementDynamicGroup<Element>::tickNetInterpolation(float dt) {
 }
 
 template <typename Element>
-void NetElementDynamicGroup<Element>::netStore(DataStream& ds) const {
+void NetElementDynamicGroup<Element>::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   ds.writeVlqU(m_idMap.size());
 
+  m_buffer.setStreamCompatibilityVersion(rules);
   for (auto& pair : m_idMap) {
     ds.writeVlqU(pair.first);
-    pair.second->netStore(m_buffer);
+    pair.second->netStore(m_buffer, rules);
     ds.write(m_buffer.data());
     m_buffer.clear();
   }
 }
 
 template <typename Element>
-void NetElementDynamicGroup<Element>::netLoad(DataStream& ds) {
+void NetElementDynamicGroup<Element>::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   m_changeData.clear();
   m_changeDataLastVersion = m_netVersion ? m_netVersion->current() : 0;
   m_idMap.clear();
@@ -188,7 +191,7 @@ void NetElementDynamicGroup<Element>::netLoad(DataStream& ds) {
     DataStreamBuffer storeBuffer(ds.read<ByteArray>());
 
     ElementPtr element = make_shared<Element>();
-    element->netLoad(storeBuffer);
+    element->netLoad(storeBuffer, rules);
     readyElement(element);
 
     m_idMap.add(id, std::move(element));
@@ -197,10 +200,11 @@ void NetElementDynamicGroup<Element>::netLoad(DataStream& ds) {
 }
 
 template <typename Element>
-bool NetElementDynamicGroup<Element>::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool NetElementDynamicGroup<Element>::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   if (fromVersion < m_changeDataLastVersion) {
     ds.write<bool>(true);
-    netStore(ds);
+    netStore(ds, rules);
     return true;
 
   } else {
@@ -220,8 +224,9 @@ bool NetElementDynamicGroup<Element>::writeNetDelta(DataStream& ds, uint64_t fro
       }
     }
 
+    m_buffer.setStreamCompatibilityVersion(rules);
     for (auto& p : m_idMap) {
-      if (p.second->writeNetDelta(m_buffer, fromVersion)) {
+      if (p.second->writeNetDelta(m_buffer, fromVersion, rules)) {
         willWrite();
         ds.writeVlqU(p.first + 1);
         ds.writeBytes(m_buffer.data());
@@ -237,10 +242,11 @@ bool NetElementDynamicGroup<Element>::writeNetDelta(DataStream& ds, uint64_t fro
 }
 
 template <typename Element>
-void NetElementDynamicGroup<Element>::readNetDelta(DataStream& ds, float interpolationTime) {
+void NetElementDynamicGroup<Element>::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   bool isFull = ds.read<bool>();
   if (isFull) {
-    netLoad(ds);
+    netLoad(ds, rules);
   } else {
     while (true) {
       uint64_t code = ds.readVlqU();
@@ -256,7 +262,7 @@ void NetElementDynamicGroup<Element>::readNetDelta(DataStream& ds, float interpo
         } else if (auto addition = changeUpdate.template ptr<ElementAddition>()) {
           ElementPtr element = make_shared<Element>();
           DataStreamBuffer storeBuffer(std::move(get<1>(*addition)));
-          element->netLoad(storeBuffer);
+          element->netLoad(storeBuffer, rules);
           readyElement(element);
           m_idMap.add(get<0>(*addition), std::move(element));
         } else if (auto removal = changeUpdate.template ptr<ElementRemoval>()) {
@@ -265,7 +271,7 @@ void NetElementDynamicGroup<Element>::readNetDelta(DataStream& ds, float interpo
       } else {
         ElementId elementId = code - 1;
         auto const& element = m_idMap.get(elementId);
-        element->readNetDelta(ds, interpolationTime);
+        element->readNetDelta(ds, interpolationTime, rules);
         if (m_interpolationEnabled)
           m_receivedDeltaIds.add(elementId);
       }
diff --git a/source/core/StarNetElementExt.hpp b/source/core/StarNetElementExt.hpp
new file mode 100644
index 0000000..50802fe
--- /dev/null
+++ b/source/core/StarNetElementExt.hpp
@@ -0,0 +1,85 @@
+#pragma once
+
+#include "StarNetElement.hpp"
+
+namespace Star {
+
+template <typename BaseNetElement>
+class NetElementOverride : public BaseNetElement {
+public:
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
+
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
+
+  typedef std::function<void(DataStream&, NetCompatibilityRules)> NetStorer;
+  typedef std::function<void(DataStream&, NetCompatibilityRules)> NetLoader;
+  typedef std::function<bool(DataStream&, uint64_t, NetCompatibilityRules)> NetDeltaWriter;
+  typedef std::function<void(DataStream&, float, NetCompatibilityRules)> NetDeltaReader;
+
+  void setNetStorer(NetStorer);
+  void setNetLoader(NetLoader);
+  void setNetDeltaWriter(NetDeltaWriter);
+  void setNetDeltaReader(NetDeltaReader);
+  void setOverrides(NetStorer netStorer, NetLoader netLoader,
+    NetDeltaWriter netDeltaWriter, NetDeltaReader netDeltaReader);
+
+private:
+  NetStorer m_netStorer;
+  NetLoader m_netLoader;
+  
+  NetDeltaWriter m_netDeltaWriter;
+  NetDeltaReader m_netDeltaReader;
+};
+
+template <typename BaseNetElement>
+void NetElementOverride<BaseNetElement>::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (m_netStorer)
+    m_netStorer(ds, rules);
+  else
+    BaseNetElement::netStore(ds, rules);
+}
+
+template <typename BaseNetElement>
+void NetElementOverride<BaseNetElement>::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (m_netLoader)
+    m_netLoader(ds, rules);
+  else
+    BaseNetElement::netLoad(ds, rules);
+}
+
+template <typename BaseNetElement>
+bool NetElementOverride<BaseNetElement>::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (m_netDeltaWriter)
+    return m_netDeltaWriter(ds, fromVersion, rules);
+  else
+    return BaseNetElement::writeNetDelta(ds, fromVersion, rules);
+}
+
+template <typename BaseNetElement>
+void NetElementOverride<BaseNetElement>::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (m_netDeltaReader)
+    m_netDeltaReader(ds, interpolationTime, rules);
+  else
+    BaseNetElement::readNetDelta(ds, interpolationTime, rules);
+}
+
+template <typename BaseNetElement>
+inline void NetElementOverride<BaseNetElement>::setNetStorer(NetStorer f) { m_netStorer = std::move(f); }
+template <typename BaseNetElement>
+inline void NetElementOverride<BaseNetElement>::setNetLoader(NetLoader f) { m_netLoader = std::move(f); }
+template <typename BaseNetElement>
+inline void NetElementOverride<BaseNetElement>::setNetDeltaWriter(NetDeltaWriter f) { m_netDeltaWriter = std::move(f); }
+template <typename BaseNetElement>
+inline void NetElementOverride<BaseNetElement>::setNetDeltaReader(NetDeltaReader f) { m_netDeltaReader = std::move(f); }
+
+template <typename BaseNetElement>
+inline void NetElementOverride<BaseNetElement>::setOverrides(NetStorer netStorer, NetLoader netLoader, NetDeltaWriter netDeltaWriter, NetDeltaReader netDeltaReader) {
+  m_netStorer = std::move(netStorer);
+  m_netLoader = std::move(netLoader);
+  m_netDeltaWriter = std::move(netDeltaWriter);
+  m_netDeltaReader = std::move(netDeltaReader);
+}
+
+}
\ No newline at end of file
diff --git a/source/core/StarNetElementFloatFields.hpp b/source/core/StarNetElementFloatFields.hpp
index 57f74a9..6c8fbcf 100644
--- a/source/core/StarNetElementFloatFields.hpp
+++ b/source/core/StarNetElementFloatFields.hpp
@@ -36,11 +36,11 @@ public:
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
   void blankNetDelta(float interpolationTime = 0.0f) override;
 
 private:
@@ -131,7 +131,8 @@ void NetElementFloating<T>::tickNetInterpolation(float dt) {
 }
 
 template <typename T>
-void NetElementFloating<T>::netStore(DataStream& ds) const {
+void NetElementFloating<T>::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   if (m_interpolationDataPoints)
     writeValue(ds, m_interpolationDataPoints->last().second);
   else
@@ -139,7 +140,8 @@ void NetElementFloating<T>::netStore(DataStream& ds) const {
 }
 
 template <typename T>
-void NetElementFloating<T>::netLoad(DataStream& ds) {
+void NetElementFloating<T>::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   m_value = readValue(ds);
   m_latestUpdateVersion = m_netVersion ? m_netVersion->current() : 0;
   if (m_interpolationDataPoints) {
@@ -149,7 +151,8 @@ void NetElementFloating<T>::netLoad(DataStream& ds) {
 }
 
 template <typename T>
-bool NetElementFloating<T>::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool NetElementFloating<T>::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   if (m_latestUpdateVersion < fromVersion)
     return false;
 
@@ -162,7 +165,7 @@ bool NetElementFloating<T>::writeNetDelta(DataStream& ds, uint64_t fromVersion)
 }
 
 template <typename T>
-void NetElementFloating<T>::readNetDelta(DataStream& ds, float interpolationTime) {
+void NetElementFloating<T>::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
   T t = readValue(ds);
 
   m_latestUpdateVersion = m_netVersion ? m_netVersion->current() : 0;
diff --git a/source/core/StarNetElementGroup.cpp b/source/core/StarNetElementGroup.cpp
index 249c978..6626e2b 100644
--- a/source/core/StarNetElementGroup.cpp
+++ b/source/core/StarNetElementGroup.cpp
@@ -21,14 +21,18 @@ void NetElementGroup::initNetVersion(NetElementVersion const* version) {
     p.first->initNetVersion(m_version);
 }
 
-void NetElementGroup::netStore(DataStream& ds) const {
+void NetElementGroup::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   for (auto& p : m_elements)
-    p.first->netStore(ds);
+    if (p.first->checkWithRules(rules))
+      p.first->netStore(ds, rules);
 }
 
-void NetElementGroup::netLoad(DataStream& ds) {
+void NetElementGroup::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   for (auto& p : m_elements)
-    p.first->netLoad(ds);
+    if (p.first->checkWithRules(rules))
+      p.first->netLoad(ds, rules);
 }
 
 void NetElementGroup::enableNetInterpolation(float extrapolationHint) {
@@ -56,17 +60,23 @@ void NetElementGroup::tickNetInterpolation(float dt) {
   }
 }
 
-bool NetElementGroup::writeNetDelta(DataStream& ds, uint64_t fromStep) const {
+bool NetElementGroup::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   if (m_elements.size() == 0) {
     return false;
   } else if (m_elements.size() == 1) {
-    return m_elements[0].first->writeNetDelta(ds, fromStep);
+    return m_elements[0].first->writeNetDelta(ds, fromVersion, rules);
   } else {
     bool deltaWritten = false;
-    for (uint64_t i = 0; i < m_elements.size(); ++i) {
-      if (m_elements[i].first->writeNetDelta(m_buffer, fromStep)) {
+    uint64_t i = 0;
+    m_buffer.setStreamCompatibilityVersion(rules);
+    for (auto& element : m_elements) {
+      if (!element.first->checkWithRules(rules))
+        continue;
+      ++i;
+      if (element.first->writeNetDelta(m_buffer, fromVersion, rules)) {
         deltaWritten = true;
-        ds.writeVlqU(i + 1);
+        ds.writeVlqU(i);
         ds.writeBytes(m_buffer.data());
         m_buffer.clear();
       }
@@ -77,23 +87,28 @@ bool NetElementGroup::writeNetDelta(DataStream& ds, uint64_t fromStep) const {
   }
 }
 
-void NetElementGroup::readNetDelta(DataStream& ds, float interpolationTime) {
+void NetElementGroup::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   if (m_elements.size() == 0) {
     throw IOException("readNetDelta called on empty NetElementGroup");
   } else if (m_elements.size() == 1) {
-    m_elements[0].first->readNetDelta(ds, interpolationTime);
+    m_elements[0].first->readNetDelta(ds, interpolationTime, rules);
   } else {
     uint64_t readIndex = ds.readVlqU();
-    for (uint64_t i = 0; i < m_elements.size(); ++i) {
+    uint64_t i = 0;
+    for (auto& element : m_elements) {
+      if (!element.first->checkWithRules(rules))
+        continue;
       if (readIndex == 0 || readIndex - 1 > i) {
         if (m_interpolationEnabled)
           m_elements[i].first->blankNetDelta(interpolationTime);
       } else if (readIndex - 1 == i) {
-        m_elements[i].first->readNetDelta(ds, interpolationTime);
+        m_elements[i].first->readNetDelta(ds, interpolationTime, rules);
         readIndex = ds.readVlqU();
       } else {
         throw IOException("group indexes out of order in NetElementGroup::readNetDelta");
       }
+      ++i;
     }
   }
 }
diff --git a/source/core/StarNetElementGroup.hpp b/source/core/StarNetElementGroup.hpp
index fd1bf58..1904a33 100644
--- a/source/core/StarNetElementGroup.hpp
+++ b/source/core/StarNetElementGroup.hpp
@@ -24,15 +24,15 @@ public:
 
   void initNetVersion(NetElementVersion const* version = nullptr) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
   void enableNetInterpolation(float extrapolationHint = 0.0f) override;
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
   void blankNetDelta(float interpolationTime) override;
 
   NetElementVersion const* netVersion() const;
diff --git a/source/core/StarNetElementSignal.hpp b/source/core/StarNetElementSignal.hpp
index 9faa127..61a108d 100644
--- a/source/core/StarNetElementSignal.hpp
+++ b/source/core/StarNetElementSignal.hpp
@@ -16,15 +16,15 @@ public:
 
   void initNetVersion(NetElementVersion const* version = nullptr) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
   void enableNetInterpolation(float extrapolationHint = 0.0f) override;
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void send(Signal signal);
   List<Signal> receive();
@@ -55,10 +55,10 @@ void NetElementSignal<Signal>::initNetVersion(NetElementVersion const* version)
 }
 
 template <typename Signal>
-void NetElementSignal<Signal>::netStore(DataStream&) const {}
+void NetElementSignal<Signal>::netStore(DataStream&, NetCompatibilityRules) const {}
 
 template <typename Signal>
-void NetElementSignal<Signal>::netLoad(DataStream&) {
+void NetElementSignal<Signal>::netLoad(DataStream&, NetCompatibilityRules) {
 }
 
 template <typename Signal>
@@ -83,7 +83,8 @@ void NetElementSignal<Signal>::tickNetInterpolation(float dt) {
 }
 
 template <typename Signal>
-bool NetElementSignal<Signal>::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool NetElementSignal<Signal>::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   size_t numToWrite = 0;
   for (auto const& p : m_signals) {
     if (p.version >= fromVersion)
@@ -103,7 +104,8 @@ bool NetElementSignal<Signal>::writeNetDelta(DataStream& ds, uint64_t fromVersio
 }
 
 template <typename Signal>
-void NetElementSignal<Signal>::readNetDelta(DataStream& ds, float interpolationTime) {
+void NetElementSignal<Signal>::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   size_t numToRead = ds.readVlqU();
   for (size_t i = 0; i < numToRead; ++i) {
     Signal s;
diff --git a/source/core/StarNetElementSyncGroup.cpp b/source/core/StarNetElementSyncGroup.cpp
index ac8da92..cd98638 100644
--- a/source/core/StarNetElementSyncGroup.cpp
+++ b/source/core/StarNetElementSyncGroup.cpp
@@ -26,23 +26,27 @@ void NetElementSyncGroup::tickNetInterpolation(float dt) {
   }
 }
 
-void NetElementSyncGroup::netStore(DataStream& ds) const {
+void NetElementSyncGroup::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   const_cast<NetElementSyncGroup*>(this)->netElementsNeedStore();
-  return NetElementGroup::netStore(ds);
+  return NetElementGroup::netStore(ds, rules);
 }
 
-void NetElementSyncGroup::netLoad(DataStream& ds) {
-  NetElementGroup::netLoad(ds);
+void NetElementSyncGroup::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
+  NetElementGroup::netLoad(ds, rules);
   netElementsNeedLoad(true);
 }
 
-bool NetElementSyncGroup::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool NetElementSyncGroup::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   const_cast<NetElementSyncGroup*>(this)->netElementsNeedStore();
-  return NetElementGroup::writeNetDelta(ds, fromVersion);
+  return NetElementGroup::writeNetDelta(ds, fromVersion, rules);
 }
 
-void NetElementSyncGroup::readNetDelta(DataStream& ds, float interpolationTime) {
-  NetElementGroup::readNetDelta(ds, interpolationTime);
+void NetElementSyncGroup::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
+  NetElementGroup::readNetDelta(ds, interpolationTime, rules);
 
   m_hasRecentChanges = true;
   m_recentDeltaTime = interpolationTime;
diff --git a/source/core/StarNetElementSyncGroup.hpp b/source/core/StarNetElementSyncGroup.hpp
index b01200b..30dafe8 100644
--- a/source/core/StarNetElementSyncGroup.hpp
+++ b/source/core/StarNetElementSyncGroup.hpp
@@ -13,11 +13,11 @@ public:
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromStep) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
   void blankNetDelta(float interpolationTime = 0.0f) override;
 
 protected:
diff --git a/source/core/StarNetElementTop.hpp b/source/core/StarNetElementTop.hpp
index 454b34f..cf3cfb4 100644
--- a/source/core/StarNetElementTop.hpp
+++ b/source/core/StarNetElementTop.hpp
@@ -1,5 +1,4 @@
-#ifndef STAR_NET_ELEMENT_TOP_HPP
-#define STAR_NET_ELEMENT_TOP_HPP
+#pragma once
 
 #include "StarNetElement.hpp"
 
@@ -12,10 +11,11 @@ class NetElementTop : public BaseNetElement {
 public:
   NetElementTop();
 
-  // Returns the state update, combined with the version code that should be
-  // passed to the next call to writeState.  If 'fromVersion' is 0, then this
-  // is a full write for an initial read of a slave NetElementTop.
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0);
+  // Writes the state update to the given DataStream then returns the version
+  // code that should be passed to the next call to writeState.  If
+  // 'fromVersion' is 0, then this is a full write for an initial read of a
+  // slave NetElementTop.
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {});
   // Reads a state produced by a call to writeState, optionally with the
   // interpolation delay time for the data contained in this state update.  If
   // the state is a full update rather than a delta, the interoplation delay
@@ -23,7 +23,7 @@ public:
   // readState, *unless* extrapolation is enabled.  If extrapolation is
   // enabled, reading a blank update calls 'blankNetDelta' which is necessary
   // to not improperly extrapolate past the end of incoming deltas.
-  void readNetState(ByteArray data, float interpolationTime = 0.0);
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {});
 
 private:
   using BaseNetElement::initNetVersion;
@@ -32,6 +32,7 @@ private:
   using BaseNetElement::writeNetDelta;
   using BaseNetElement::readNetDelta;
   using BaseNetElement::blankNetDelta;
+  using BaseNetElement::checkWithRules;
 
   NetElementVersion m_netVersion;
 };
@@ -42,41 +43,34 @@ NetElementTop<BaseNetElement>::NetElementTop() {
 }
 
 template <typename BaseNetElement>
-pair<ByteArray, uint64_t> NetElementTop<BaseNetElement>::writeNetState(uint64_t fromVersion) {
+pair<ByteArray, uint64_t> NetElementTop<BaseNetElement>::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
   if (fromVersion == 0) {
-    DataStreamBuffer ds;
     ds.write<bool>(true);
-    BaseNetElement::netStore(ds);
-    m_netVersion.increment();
-    return {ds.takeData(), m_netVersion.current()};
-
+    BaseNetElement::netStore(ds, rules);
+    return {ds.takeData(), m_netVersion.increment()};
   } else {
-    DataStreamBuffer ds;
     ds.write<bool>(false);
-    if (!BaseNetElement::writeNetDelta(ds, fromVersion)) {
+    if (!BaseNetElement::writeNetDelta(ds, fromVersion, rules))
       return {ByteArray(), m_netVersion.current()};
-    } else {
-      m_netVersion.increment();
-      return {ds.takeData(), m_netVersion.current()};
-    }
+    else
+      return {ds.takeData(), m_netVersion.increment()};
   }
 }
 
 template <typename BaseNetElement>
-void NetElementTop<BaseNetElement>::readNetState(ByteArray data, float interpolationTime) {
+void NetElementTop<BaseNetElement>::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
   if (data.empty()) {
     BaseNetElement::blankNetDelta(interpolationTime);
-
   } else {
     DataStreamBuffer ds(std::move(data));
-
+    ds.setStreamCompatibilityVersion(rules);
     if (ds.read<bool>())
-      BaseNetElement::netLoad(ds);
+      BaseNetElement::netLoad(ds, rules);
     else
-      BaseNetElement::readNetDelta(ds, interpolationTime);
+      BaseNetElement::readNetDelta(ds, interpolationTime, rules);
   }
 }
 
-}
-
-#endif
+}
\ No newline at end of file
diff --git a/source/frontend/StarTeamBar.hpp b/source/frontend/StarTeamBar.hpp
index ca50452..2ca40d6 100644
--- a/source/frontend/StarTeamBar.hpp
+++ b/source/frontend/StarTeamBar.hpp
@@ -1,5 +1,4 @@
-#ifndef STAR_TEAMBAR_HPP
-#define STAR_TEAMBAR_HPP
+#pragma once
 
 #include "StarPane.hpp"
 #include "StarUuid.hpp"
@@ -113,6 +112,4 @@ private:
   friend class TeamMemberMenu;
 };
 
-}
-
-#endif
+}
\ No newline at end of file
diff --git a/source/game/StarClientContext.cpp b/source/game/StarClientContext.cpp
index a91c40e..3061368 100644
--- a/source/game/StarClientContext.cpp
+++ b/source/game/StarClientContext.cpp
@@ -77,11 +77,12 @@ ShipUpgrades ClientContext::shipUpgrades() const {
   return m_shipUpgrades.get();
 }
 
-void ClientContext::readUpdate(ByteArray data) {
+void ClientContext::readUpdate(ByteArray data, NetCompatibilityRules rules) {
   if (data.empty())
     return;
 
   DataStreamBuffer ds(std::move(data));
+  ds.setStreamCompatibilityVersion(rules);
 
   m_rpc->receive(ds.read<ByteArray>());
 
@@ -89,10 +90,10 @@ void ClientContext::readUpdate(ByteArray data) {
   if (!shipUpdates.empty())
     m_newShipUpdates.merge(DataStreamBuffer::deserialize<WorldChunks>(std::move(shipUpdates)), true);
 
-  m_netGroup.readNetState(ds.read<ByteArray>());
+  m_netGroup.readNetState(ds.read<ByteArray>(), 0.0f, rules);
 }
 
-ByteArray ClientContext::writeUpdate() {
+ByteArray ClientContext::writeUpdate(NetCompatibilityRules rules) {
   return m_rpc->send();
 }
 
@@ -104,4 +105,12 @@ ConnectionId ClientContext::connectionId() const {
   return m_connectionId;
 }
 
+void ClientContext::setNetCompatibilityRules(NetCompatibilityRules netCompatibilityRules) {
+  m_netCompatibilityRules = netCompatibilityRules;
+}
+
+NetCompatibilityRules ClientContext::netCompatibilityRules() const {
+  return m_netCompatibilityRules;
+}
+
 }
diff --git a/source/game/StarClientContext.hpp b/source/game/StarClientContext.hpp
index 5cdd727..9c08d32 100644
--- a/source/game/StarClientContext.hpp
+++ b/source/game/StarClientContext.hpp
@@ -40,16 +40,20 @@ public:
   WorldChunks newShipUpdates();
   ShipUpgrades shipUpgrades() const;
 
-  void readUpdate(ByteArray data);
-  ByteArray writeUpdate();
+  void readUpdate(ByteArray data, NetCompatibilityRules rules);
+  ByteArray writeUpdate(NetCompatibilityRules rules);
 
   void setConnectionId(ConnectionId connectionId);
   ConnectionId connectionId() const;
 
+  void setNetCompatibilityRules(NetCompatibilityRules netCompatibilityRules);
+  NetCompatibilityRules netCompatibilityRules() const;
+
 private:
   Uuid m_serverUuid;
   Uuid m_playerUuid;
   ConnectionId m_connectionId = 0;
+  NetCompatibilityRules m_netCompatibilityRules;
 
   JsonRpcPtr m_rpc;
 
diff --git a/source/game/StarEntityFactory.cpp b/source/game/StarEntityFactory.cpp
index 333dec1..0202ea7 100644
--- a/source/game/StarEntityFactory.cpp
+++ b/source/game/StarEntityFactory.cpp
@@ -40,57 +40,57 @@ EntityFactory::EntityFactory() {
   m_versioningDatabase = root.versioningDatabase();
 }
 
-ByteArray EntityFactory::netStoreEntity(EntityPtr const& entity) const {
+ByteArray EntityFactory::netStoreEntity(EntityPtr const& entity, NetCompatibilityRules rules) const {
   RecursiveMutexLocker locker(m_mutex);
 
   if (auto player = as<Player>(entity)) {
-    return player->netStore();
+    return player->netStore(rules);
   } else if (auto monster = as<Monster>(entity)) {
-    return monster->netStore();
+    return monster->netStore(rules);
   } else if (auto object = as<Object>(entity)) {
-    return object->netStore();
+    return object->netStore(rules);
   } else if (auto plant = as<Plant>(entity)) {
-    return plant->netStore();
+    return plant->netStore(rules);
   } else if (auto plantDrop = as<PlantDrop>(entity)) {
-    return plantDrop->netStore();
+    return plantDrop->netStore(rules);
   } else if (auto projectile = as<Projectile>(entity)) {
-    return projectile->netStore();
+    return projectile->netStore(rules);
   } else if (auto itemDrop = as<ItemDrop>(entity)) {
-    return itemDrop->netStore();
+    return itemDrop->netStore(rules);
   } else if (auto npc = as<Npc>(entity)) {
-    return npc->netStore();
+    return npc->netStore(rules);
   } else if (auto stagehand = as<Stagehand>(entity)) {
-    return stagehand->netStore();
+    return stagehand->netStore(rules);
   } else if (auto vehicle = as<Vehicle>(entity)) {
-    return m_vehicleDatabase->netStore(vehicle);
+    return m_vehicleDatabase->netStore(vehicle, rules);
   } else {
     throw EntityFactoryException::format("Don't know how to make net store for entity type '{}'", EntityTypeNames.getRight(entity->entityType()));
   }
 }
 
-EntityPtr EntityFactory::netLoadEntity(EntityType type, ByteArray const& netStore) const {
+EntityPtr EntityFactory::netLoadEntity(EntityType type, ByteArray const& netStore, NetCompatibilityRules rules) const {
   RecursiveMutexLocker locker(m_mutex);
 
   if (type == EntityType::Player) {
-    return m_playerFactory->netLoadPlayer(netStore);
+    return m_playerFactory->netLoadPlayer(netStore, rules);
   } else if (type == EntityType::Monster) {
-    return m_monsterDatabase->netLoadMonster(netStore);
+    return m_monsterDatabase->netLoadMonster(netStore, rules);
   } else if (type == EntityType::Object) {
-    return m_objectDatabase->netLoadObject(netStore);
+    return m_objectDatabase->netLoadObject(netStore, rules);
   } else if (type == EntityType::Plant) {
-    return make_shared<Plant>(netStore);
+    return make_shared<Plant>(netStore, rules);
   } else if (type == EntityType::PlantDrop) {
-    return make_shared<PlantDrop>(netStore);
+    return make_shared<PlantDrop>(netStore, rules);
   } else if (type == EntityType::Projectile) {
-    return m_projectileDatabase->netLoadProjectile(netStore);
+    return m_projectileDatabase->netLoadProjectile(netStore, rules);
   } else if (type == EntityType::ItemDrop) {
-    return make_shared<ItemDrop>(netStore);
+    return make_shared<ItemDrop>(netStore, rules);
   } else if (type == EntityType::Npc) {
-    return m_npcDatabase->netLoadNpc(netStore);
+    return m_npcDatabase->netLoadNpc(netStore, rules);
   } else if (type == EntityType::Stagehand) {
-    return make_shared<Stagehand>(netStore);
+    return make_shared<Stagehand>(netStore, rules);
   } else if (type == EntityType::Vehicle) {
-    return m_vehicleDatabase->netLoad(netStore);
+    return m_vehicleDatabase->netLoad(netStore, rules);
   } else {
     throw EntityFactoryException::format("Don't know how to create entity type '{}' from net store", EntityTypeNames.getRight(type));
   }
diff --git a/source/game/StarEntityFactory.hpp b/source/game/StarEntityFactory.hpp
index 09d4e99..7d5c014 100644
--- a/source/game/StarEntityFactory.hpp
+++ b/source/game/StarEntityFactory.hpp
@@ -20,8 +20,8 @@ class EntityFactory {
 public:
   EntityFactory();
 
-  ByteArray netStoreEntity(EntityPtr const& entity) const;
-  EntityPtr netLoadEntity(EntityType type, ByteArray const& netStore) const;
+  ByteArray netStoreEntity(EntityPtr const& entity, NetCompatibilityRules rules = {}) const;
+  EntityPtr netLoadEntity(EntityType type, ByteArray const& netStore, NetCompatibilityRules rules = {}) const;
 
   Json diskStoreEntity(EntityPtr const& entity) const;
   EntityPtr diskLoadEntity(EntityType type, Json const& diskStore) const;
diff --git a/source/game/StarHumanoid.cpp b/source/game/StarHumanoid.cpp
index 47368b1..d140881 100644
--- a/source/game/StarHumanoid.cpp
+++ b/source/game/StarHumanoid.cpp
@@ -243,6 +243,49 @@ EnumMap<Humanoid::State> const Humanoid::StateNames{
 };
 
 Humanoid::Humanoid(Json const& config) {
+  loadConfig(config);
+
+  m_twoHanded = false;
+  m_primaryHand.holdingItem = false;
+  m_altHand.holdingItem = false;
+
+  m_movingBackwards = false;
+  m_altHand.angle = 0;
+  m_facingDirection = Direction::Left;
+  m_rotation = 0;
+  m_scale = Vec2F::filled(1.f);
+  m_drawVaporTrail = false;
+  m_state = State::Idle;
+  m_emoteState = HumanoidEmote::Idle;
+  m_dance = {};
+
+  m_primaryHand.angle = 0;
+  m_animationTimer = m_emoteAnimationTimer = m_danceTimer = 0.0f;
+}
+
+Humanoid::Humanoid(HumanoidIdentity const& identity)
+  : Humanoid(Root::singleton().speciesDatabase()->species(identity.species)->humanoidConfig()) {
+  setIdentity(identity);
+}
+
+void Humanoid::setIdentity(HumanoidIdentity const& identity) {
+  m_identity = identity;
+  m_headFrameset = getHeadFromIdentity();
+  m_bodyFrameset = getBodyFromIdentity();
+  m_emoteFrameset = getFacialEmotesFromIdentity();
+  m_hairFrameset = getHairFromIdentity();
+  m_facialHairFrameset = getFacialHairFromIdentity();
+  m_facialMaskFrameset = getFacialMaskFromIdentity();
+  m_backArmFrameset = getBackArmFromIdentity();
+  m_frontArmFrameset = getFrontArmFromIdentity();
+  m_vaporTrailFrameset = getVaporTrailFrameset();
+}
+
+HumanoidIdentity const& Humanoid::identity() const {
+  return m_identity;
+}
+
+void Humanoid::loadConfig(Json const& config) {
   m_timing = HumanoidTiming(config.getObject("humanoidTiming"));
 
   m_globalOffset = jsonToVec2F(config.get("globalOffset")) / TilePixels;
@@ -271,10 +314,13 @@ Humanoid::Humanoid(Json const& config) {
   m_armWalkSeq = jsonToIntList(config.get("armWalkSeq"));
   m_armRunSeq = jsonToIntList(config.get("armRunSeq"));
 
+  m_walkBob.clear();
   for (auto const& v : config.get("walkBob").toArray())
     m_walkBob.append(v.toDouble() / TilePixels);
+  m_runBob.clear();
   for (auto const& v : config.get("runBob").toArray())
     m_runBob.append(v.toDouble() / TilePixels);
+  m_swimBob.clear();
   for (auto const& v : config.get("swimBob").toArray())
     m_swimBob.append(v.toDouble() / TilePixels);
 
@@ -290,46 +336,6 @@ Humanoid::Humanoid(Json const& config) {
   m_particleEmitters = config.get("particleEmitters");
 
   m_defaultMovementParameters = config.get("movementParameters");
-
-  m_twoHanded = false;
-  m_primaryHand.holdingItem = false;
-  m_altHand.holdingItem = false;
-
-  m_movingBackwards = false;
-  m_altHand.angle = 0;
-  m_facingDirection = Direction::Left;
-  m_rotation = 0;
-  m_scale = Vec2F::filled(1.f);
-  m_drawVaporTrail = false;
-  m_state = State::Idle;
-  m_emoteState = HumanoidEmote::Idle;
-  m_dance = {};
-  m_emoteAnimationTimer = 0;
-
-  m_primaryHand.angle = 0;
-  m_animationTimer = 0.0f;
-}
-
-Humanoid::Humanoid(HumanoidIdentity const& identity)
-  : Humanoid(Root::singleton().speciesDatabase()->species(identity.species)->humanoidConfig()) {
-  setIdentity(identity);
-}
-
-void Humanoid::setIdentity(HumanoidIdentity const& identity) {
-  m_identity = identity;
-  m_headFrameset = getHeadFromIdentity();
-  m_bodyFrameset = getBodyFromIdentity();
-  m_emoteFrameset = getFacialEmotesFromIdentity();
-  m_hairFrameset = getHairFromIdentity();
-  m_facialHairFrameset = getFacialHairFromIdentity();
-  m_facialMaskFrameset = getFacialMaskFromIdentity();
-  m_backArmFrameset = getBackArmFromIdentity();
-  m_frontArmFrameset = getFrontArmFromIdentity();
-  m_vaporTrailFrameset = getVaporTrailFrameset();
-}
-
-HumanoidIdentity const& Humanoid::identity() const {
-  return m_identity;
 }
 
 void Humanoid::setHeadArmorDirectives(Directives directives) {
diff --git a/source/game/StarHumanoid.hpp b/source/game/StarHumanoid.hpp
index 283f7e9..c83ddb5 100644
--- a/source/game/StarHumanoid.hpp
+++ b/source/game/StarHumanoid.hpp
@@ -125,6 +125,8 @@ public:
   void setIdentity(HumanoidIdentity const& identity);
   HumanoidIdentity const& identity() const;
 
+  void loadConfig(Json const& config);
+
   // All of the image identifiers here are meant to be image *base* names, with
   // a collection of frames specific to each piece.  If an image is set to
   // empty string, it is disabled.
diff --git a/source/game/StarItemDrop.cpp b/source/game/StarItemDrop.cpp
index bc3d15f..4d9dab1 100644
--- a/source/game/StarItemDrop.cpp
+++ b/source/game/StarItemDrop.cpp
@@ -92,9 +92,9 @@ ItemDrop::ItemDrop(Json const& diskStore)
   m_itemDescriptor.set(m_item->descriptor());
 }
 
-ItemDrop::ItemDrop(ByteArray store)
-  : ItemDrop() {
+ItemDrop::ItemDrop(ByteArray store, NetCompatibilityRules rules) : ItemDrop() {
   DataStreamBuffer ds(std::move(store));
+  ds.setStreamCompatibilityVersion(rules);
 
   Root::singleton().itemDatabase()->loadItem(ds.read<ItemDescriptor>(), m_item);
   ds.read(m_eternal);
@@ -116,8 +116,9 @@ Json ItemDrop::diskStore() const {
   };
 }
 
-ByteArray ItemDrop::netStore() const {
+ByteArray ItemDrop::netStore(NetCompatibilityRules rules) const {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
 
   ds.write(itemSafeDescriptor(m_item));
   ds.write(m_eternal);
@@ -146,12 +147,12 @@ String ItemDrop::description() const {
   return m_item->description();
 }
 
-pair<ByteArray, uint64_t> ItemDrop::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> ItemDrop::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void ItemDrop::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void ItemDrop::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void ItemDrop::enableInterpolation(float extrapolationHint) {
diff --git a/source/game/StarItemDrop.hpp b/source/game/StarItemDrop.hpp
index 3d6e931..c551c01 100644
--- a/source/game/StarItemDrop.hpp
+++ b/source/game/StarItemDrop.hpp
@@ -27,10 +27,10 @@ public:
 
   ItemDrop(ItemPtr item);
   ItemDrop(Json const& diskStore);
-  ItemDrop(ByteArray netStore);
+  ItemDrop(ByteArray netStore, NetCompatibilityRules rules = {});
 
   Json diskStore() const;
-  ByteArray netStore() const;
+  ByteArray netStore(NetCompatibilityRules rules = {}) const;
 
   EntityType entityType() const override;
 
@@ -39,8 +39,8 @@ public:
 
   String description() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint = 0.0f) override;
   void disableInterpolation() override;
diff --git a/source/game/StarMonster.cpp b/source/game/StarMonster.cpp
index 05eaeb3..d9ce986 100644
--- a/source/game/StarMonster.cpp
+++ b/source/game/StarMonster.cpp
@@ -110,8 +110,8 @@ Json Monster::diskStore() const {
   };
 }
 
-ByteArray Monster::netStore() {
-  return Root::singleton().monsterDatabase()->writeMonsterVariant(m_monsterVariant);
+ByteArray Monster::netStore(NetCompatibilityRules rules) {
+  return Root::singleton().monsterDatabase()->writeMonsterVariant(m_monsterVariant, rules);
 }
 
 EntityType Monster::entityType() const {
@@ -210,12 +210,12 @@ Vec2F Monster::velocity() const {
   return m_movementController->velocity();
 }
 
-pair<ByteArray, uint64_t> Monster::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Monster::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Monster::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void Monster::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void Monster::enableInterpolation(float extrapolationHint) {
diff --git a/source/game/StarMonster.hpp b/source/game/StarMonster.hpp
index d6cae3e..5c964e3 100644
--- a/source/game/StarMonster.hpp
+++ b/source/game/StarMonster.hpp
@@ -42,7 +42,7 @@ public:
   Monster(Json const& diskStore);
 
   Json diskStore() const;
-  ByteArray netStore();
+  ByteArray netStore(NetCompatibilityRules rules = {});
 
   EntityType entityType() const override;
   ClientEntityMode clientEntityMode() const override;
@@ -60,8 +60,8 @@ public:
 
   RectF collisionArea() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint) override;
   void disableInterpolation() override;
diff --git a/source/game/StarMonsterDatabase.cpp b/source/game/StarMonsterDatabase.cpp
index 963cf87..2b86d44 100644
--- a/source/game/StarMonsterDatabase.cpp
+++ b/source/game/StarMonsterDatabase.cpp
@@ -170,8 +170,9 @@ MonsterVariant MonsterDatabase::monsterVariant(String const& typeName, uint64_t
     });
 }
 
-ByteArray MonsterDatabase::writeMonsterVariant(MonsterVariant const& variant) const {
+ByteArray MonsterDatabase::writeMonsterVariant(MonsterVariant const& variant, NetCompatibilityRules rules) const {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
 
   ds.write(variant.type);
   ds.write(variant.seed);
@@ -180,8 +181,9 @@ ByteArray MonsterDatabase::writeMonsterVariant(MonsterVariant const& variant) co
   return ds.data();
 }
 
-MonsterVariant MonsterDatabase::readMonsterVariant(ByteArray const& data) const {
+MonsterVariant MonsterDatabase::readMonsterVariant(ByteArray const& data, NetCompatibilityRules rules) const {
   DataStreamBuffer ds(data);
+  ds.setStreamCompatibilityVersion(rules);
 
   String type = ds.read<String>();
   uint64_t seed = ds.read<uint64_t>();
@@ -216,8 +218,8 @@ MonsterPtr MonsterDatabase::diskLoadMonster(Json const& diskStore) const {
   return make_shared<Monster>(diskStore);
 }
 
-MonsterPtr MonsterDatabase::netLoadMonster(ByteArray const& netStore) const {
-  return make_shared<Monster>(readMonsterVariant(netStore));
+MonsterPtr MonsterDatabase::netLoadMonster(ByteArray const& netStore, NetCompatibilityRules rules) const {
+  return make_shared<Monster>(readMonsterVariant(netStore, rules));
 }
 
 List<Drawable> MonsterDatabase::monsterPortrait(MonsterVariant const& variant) const {
diff --git a/source/game/StarMonsterDatabase.hpp b/source/game/StarMonsterDatabase.hpp
index 9147542..0220267 100644
--- a/source/game/StarMonsterDatabase.hpp
+++ b/source/game/StarMonsterDatabase.hpp
@@ -96,8 +96,8 @@ public:
   MonsterVariant randomMonster(String const& typeName, Json const& uniqueParameters = JsonObject()) const;
   MonsterVariant monsterVariant(String const& typeName, uint64_t seed, Json const& uniqueParameters = JsonObject()) const;
 
-  ByteArray writeMonsterVariant(MonsterVariant const& variant) const;
-  MonsterVariant readMonsterVariant(ByteArray const& data) const;
+  ByteArray writeMonsterVariant(MonsterVariant const& variant, NetCompatibilityRules rules = {}) const;
+  MonsterVariant readMonsterVariant(ByteArray const& data, NetCompatibilityRules rules = {}) const;
 
   Json writeMonsterVariantToJson(MonsterVariant const& mVar) const;
   MonsterVariant readMonsterVariantFromJson(Json const& variant) const;
@@ -106,7 +106,7 @@ public:
   // whatever world they're spawned in.
   MonsterPtr createMonster(MonsterVariant monsterVariant, Maybe<float> level = {}, Json uniqueParameters = {}) const;
   MonsterPtr diskLoadMonster(Json const& diskStore) const;
-  MonsterPtr netLoadMonster(ByteArray const& netStore) const;
+  MonsterPtr netLoadMonster(ByteArray const& netStore, NetCompatibilityRules rules = {}) const;
 
   List<Drawable> monsterPortrait(MonsterVariant const& variant) const;
 
diff --git a/source/game/StarNetPackets.cpp b/source/game/StarNetPackets.cpp
index b8605ed..dd80d76 100644
--- a/source/game/StarNetPackets.cpp
+++ b/source/game/StarNetPackets.cpp
@@ -5,6 +5,7 @@
 namespace Star {
 
 VersionNumber const StarProtocolVersion = 747;
+VersionNumber const OpenProtocolVersion = 1;
 
 EnumMap<PacketType> const PacketTypeNames{
   {PacketType::ProtocolRequest, "ProtocolRequest"},
diff --git a/source/game/StarNetPackets.hpp b/source/game/StarNetPackets.hpp
index 6181b30..e68a045 100644
--- a/source/game/StarNetPackets.hpp
+++ b/source/game/StarNetPackets.hpp
@@ -14,6 +14,7 @@
 #include "StarWiring.hpp"
 #include "StarClientContext.hpp"
 #include "StarSystemWorld.hpp"
+#include "StarNetCompatibility.hpp"
 
 namespace Star {
 
@@ -22,6 +23,7 @@ STAR_STRUCT(Packet);
 STAR_EXCEPTION(StarPacketException, IOException);
 
 extern VersionNumber const StarProtocolVersion;
+extern VersionNumber const OpenProtocolVersion;
 
 // Packet types sent between the client and server over a NetSocket.  Does not
 // correspond to actual packets, simply logical portions of NetSocket data.
diff --git a/source/game/StarNpc.cpp b/source/game/StarNpc.cpp
index c68fd08..388f6e5 100644
--- a/source/game/StarNpc.cpp
+++ b/source/game/StarNpc.cpp
@@ -152,8 +152,8 @@ Json Npc::diskStore() const {
   };
 }
 
-ByteArray Npc::netStore() {
-  return Root::singleton().npcDatabase()->writeNpcVariant(m_npcVariant);
+ByteArray Npc::netStore(NetCompatibilityRules rules) {
+  return Root::singleton().npcDatabase()->writeNpcVariant(m_npcVariant, rules);
 }
 
 EntityType Npc::entityType() const {
@@ -252,7 +252,7 @@ RectF Npc::collisionArea() const {
   return m_movementController->collisionPoly().boundBox();
 }
 
-pair<ByteArray, uint64_t> Npc::writeNetState(uint64_t fromVersion) {
+pair<ByteArray, uint64_t> Npc::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
   // client-side npcs error nearby vanilla NPC scripts because callScriptedEntity
   // for now, scrungle the collision poly to avoid their queries. hacky :(
   if (m_npcVariant.overrides && m_npcVariant.overrides.getBool("overrideNetPoly", false)) {
@@ -260,18 +260,18 @@ pair<ByteArray, uint64_t> Npc::writeNetState(uint64_t fromVersion) {
       if (*mode == EntityMode::Master && connectionForEntity(entityId()) != ServerConnectionId) {
         PolyF poly = m_movementController->collisionPoly();
         m_movementController->setCollisionPoly({ { 0.0f, -3.402823466e+38F }});
-        auto result = m_netGroup.writeNetState(fromVersion);
+        auto result = m_netGroup.writeNetState(fromVersion, rules);
         m_movementController->setCollisionPoly(poly);
         return result;
       }
     }
   }
 
-  return m_netGroup.writeNetState(fromVersion);
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Npc::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void Npc::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 String Npc::description() const {
diff --git a/source/game/StarNpc.hpp b/source/game/StarNpc.hpp
index ab8bc0f..0b22702 100644
--- a/source/game/StarNpc.hpp
+++ b/source/game/StarNpc.hpp
@@ -42,11 +42,12 @@ class Npc
     public virtual PhysicsEntity,
     public virtual EmoteEntity {
 public:
+  Npc(ByteArray const& netStore, NetCompatibilityRules rules = {});
   Npc(NpcVariant const& npcVariant);
   Npc(NpcVariant const& npcVariant, Json const& initialState);
 
   Json diskStore() const;
-  ByteArray netStore();
+  ByteArray netStore(NetCompatibilityRules rules = {});
 
   EntityType entityType() const override;
   ClientEntityMode clientEntityMode() const override;
@@ -66,8 +67,8 @@ public:
 
   RectF collisionArea() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint = 0.0f) override;
   void disableInterpolation() override;
diff --git a/source/game/StarNpcDatabase.cpp b/source/game/StarNpcDatabase.cpp
index bd70df5..392b29d 100644
--- a/source/game/StarNpcDatabase.cpp
+++ b/source/game/StarNpcDatabase.cpp
@@ -157,8 +157,9 @@ NpcVariant NpcDatabase::generateNpcVariant(
   return variant;
 }
 
-ByteArray NpcDatabase::writeNpcVariant(NpcVariant const& variant) const {
+ByteArray NpcDatabase::writeNpcVariant(NpcVariant const& variant, NetCompatibilityRules rules) const {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
 
   ds.write(variant.species);
   ds.write(variant.typeName);
@@ -179,8 +180,9 @@ ByteArray NpcDatabase::writeNpcVariant(NpcVariant const& variant) const {
   return ds.data();
 }
 
-NpcVariant NpcDatabase::readNpcVariant(ByteArray const& data) const {
+NpcVariant NpcDatabase::readNpcVariant(ByteArray const& data, NetCompatibilityRules rules) const {
   DataStreamBuffer ds(data);
+  ds.setStreamCompatibilityVersion(rules);
 
   NpcVariant variant;
 
@@ -325,8 +327,8 @@ NpcPtr NpcDatabase::diskLoadNpc(Json const& diskStore) const {
   return make_shared<Npc>(npcVariant, diskStore);
 }
 
-NpcPtr NpcDatabase::netLoadNpc(ByteArray const& netStore) const {
-  return make_shared<Npc>(readNpcVariant(netStore));
+NpcPtr NpcDatabase::netLoadNpc(ByteArray const& netStore, NetCompatibilityRules rules) const {
+  return make_shared<Npc>(readNpcVariant(netStore, rules));
 }
 
 List<Drawable> NpcDatabase::npcPortrait(NpcVariant const& npcVariant, PortraitMode mode) const {
diff --git a/source/game/StarNpcDatabase.hpp b/source/game/StarNpcDatabase.hpp
index 01dec97..a97d0f5 100644
--- a/source/game/StarNpcDatabase.hpp
+++ b/source/game/StarNpcDatabase.hpp
@@ -58,15 +58,15 @@ public:
   NpcVariant generateNpcVariant(String const& species, String const& typeName, float level) const;
   NpcVariant generateNpcVariant(String const& species, String const& typeName, float level, uint64_t seed, Json const& overrides) const;
 
-  ByteArray writeNpcVariant(NpcVariant const& variant) const;
-  NpcVariant readNpcVariant(ByteArray const& data) const;
+  ByteArray writeNpcVariant(NpcVariant const& variant, NetCompatibilityRules rules = {}) const;
+  NpcVariant readNpcVariant(ByteArray const& data, NetCompatibilityRules rules = {}) const;
 
   Json writeNpcVariantToJson(NpcVariant const& variant) const;
   NpcVariant readNpcVariantFromJson(Json const& data) const;
 
   NpcPtr createNpc(NpcVariant const& npcVariant) const;
-  NpcPtr diskLoadNpc(Json const& diskStoree) const;
-  NpcPtr netLoadNpc(ByteArray const& netStore) const;
+  NpcPtr diskLoadNpc(Json const& diskStore) const;
+  NpcPtr netLoadNpc(ByteArray const& netStore, NetCompatibilityRules rules = {}) const;
 
   List<Drawable> npcPortrait(NpcVariant const& npcVariant, PortraitMode mode) const;
 
diff --git a/source/game/StarObject.cpp b/source/game/StarObject.cpp
index ece0b20..66f7917 100644
--- a/source/game/StarObject.cpp
+++ b/source/game/StarObject.cpp
@@ -118,8 +118,9 @@ Json Object::diskStore() const {
   return writeStoredData().setAll({{"name", m_config->name}, {"parameters", m_parameters.baseMap()}});
 }
 
-ByteArray Object::netStore() {
+ByteArray Object::netStore(NetCompatibilityRules rules) {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
   ds.write(m_config->name);
   ds.write<Json>(m_parameters.baseMap());
   return ds.takeData();
@@ -297,13 +298,12 @@ RectF Object::metaBoundBox() const {
   }
 }
 
-pair<ByteArray, uint64_t> Object::writeNetState(uint64_t fromVersion) {
-  DataStreamBuffer ds;
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Object::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Object::readNetState(ByteArray delta, float interpolationTime) {
-  m_netGroup.readNetState(std::move(delta), interpolationTime);
+void Object::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 Vec2I Object::tilePosition() const {
diff --git a/source/game/StarObject.hpp b/source/game/StarObject.hpp
index a797842..e768ca8 100644
--- a/source/game/StarObject.hpp
+++ b/source/game/StarObject.hpp
@@ -37,7 +37,7 @@ public:
   Object(ObjectConfigConstPtr config, Json const& parameters = JsonObject());
 
   Json diskStore() const;
-  ByteArray netStore();
+  ByteArray netStore(NetCompatibilityRules rules = {});
 
   virtual EntityType entityType() const override;
   virtual ClientEntityMode clientEntityMode() const override;
@@ -48,8 +48,8 @@ public:
   virtual Vec2F position() const override;
   virtual RectF metaBoundBox() const override;
 
-  virtual pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  virtual void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  virtual pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  virtual void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   virtual String description() const override;
 
diff --git a/source/game/StarObjectDatabase.cpp b/source/game/StarObjectDatabase.cpp
index 8ed56e4..71eb166 100644
--- a/source/game/StarObjectDatabase.cpp
+++ b/source/game/StarObjectDatabase.cpp
@@ -380,8 +380,9 @@ ObjectPtr ObjectDatabase::diskLoadObject(Json const& diskStore) const {
   return object;
 }
 
-ObjectPtr ObjectDatabase::netLoadObject(ByteArray const& netStore) const {
+ObjectPtr ObjectDatabase::netLoadObject(ByteArray const& netStore, NetCompatibilityRules rules) const {
   DataStreamBuffer ds(netStore);
+  ds.setStreamCompatibilityVersion(rules);
   String name = ds.read<String>();
   Json parameters = ds.read<Json>();
   return createObject(name, parameters);
diff --git a/source/game/StarObjectDatabase.hpp b/source/game/StarObjectDatabase.hpp
index ca44c2e..b431445 100644
--- a/source/game/StarObjectDatabase.hpp
+++ b/source/game/StarObjectDatabase.hpp
@@ -198,7 +198,7 @@ public:
 
   ObjectPtr createObject(String const& objectName, Json const& objectParameters = JsonObject()) const;
   ObjectPtr diskLoadObject(Json const& diskStore) const;
-  ObjectPtr netLoadObject(ByteArray const& netStore) const;
+  ObjectPtr netLoadObject(ByteArray const& netStore, NetCompatibilityRules rules = {}) const;
 
   bool canPlaceObject(World const* world, Vec2I const& position, String const& objectName) const;
   // If the object is placeable in the given position, creates the given object
diff --git a/source/game/StarPlant.cpp b/source/game/StarPlant.cpp
index 7b4e426..32e1575 100644
--- a/source/game/StarPlant.cpp
+++ b/source/game/StarPlant.cpp
@@ -411,8 +411,9 @@ Json Plant::diskStore() const {
   };
 }
 
-ByteArray Plant::netStore() const {
+ByteArray Plant::netStore(NetCompatibilityRules rules) const {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
   ds.viwrite(m_tilePosition[0]);
   ds.viwrite(m_tilePosition[1]);
   ds.write(m_ceiling);
@@ -423,7 +424,7 @@ ByteArray Plant::netStore() const {
   ds.write(m_ephemeral);
   ds.write(m_tileDamageParameters);
   ds.write(m_fallsWhenDead);
-  m_tileDamageStatus.netStore(ds);
+  m_tileDamageStatus.netStore(ds, rules);
   ds.write(writePieces());
 
   return ds.takeData();
@@ -534,7 +535,7 @@ Plant::Plant(Json const& diskStore) : Plant() {
   setupNetStates();
 }
 
-Plant::Plant(ByteArray const& netStore) : Plant() {
+Plant::Plant(ByteArray const& netStore, NetCompatibilityRules rules) : Plant() {
   m_broken = false;
   m_tilePosition = Vec2I();
   m_ceiling = false;
@@ -545,6 +546,7 @@ Plant::Plant(ByteArray const& netStore) : Plant() {
   m_piecesUpdated = true;
 
   DataStreamBuffer ds(netStore);
+  ds.setStreamCompatibilityVersion(rules);
   ds.viread(m_tilePosition[0]);
   ds.viread(m_tilePosition[1]);
   ds.read(m_ceiling);
@@ -555,7 +557,7 @@ Plant::Plant(ByteArray const& netStore) : Plant() {
   ds.read(m_ephemeral);
   ds.read(m_tileDamageParameters);
   ds.read(m_fallsWhenDead);
-  m_tileDamageStatus.netLoad(ds);
+  m_tileDamageStatus.netLoad(ds, rules);
   readPieces(ds.read<ByteArray>());
 
   setupNetStates();
@@ -586,12 +588,12 @@ void Plant::init(World* world, EntityId entityId, EntityMode mode) {
   m_tilePosition = world->geometry().xwrap(m_tilePosition);
 }
 
-pair<ByteArray, uint64_t> Plant::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Plant::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Plant::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void Plant::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void Plant::enableInterpolation(float extrapolationHint) {
diff --git a/source/game/StarPlant.hpp b/source/game/StarPlant.hpp
index 53aed5f..ddb9501 100644
--- a/source/game/StarPlant.hpp
+++ b/source/game/StarPlant.hpp
@@ -57,10 +57,10 @@ public:
   Plant(GrassVariant const& config, uint64_t seed);
   Plant(BushVariant const& config, uint64_t seed);
   Plant(Json const& diskStore);
-  Plant(ByteArray const& netStore);
+  Plant(ByteArray const& netStore, NetCompatibilityRules rules = {});
 
   Json diskStore() const;
-  ByteArray netStore() const;
+  ByteArray netStore(NetCompatibilityRules rules = {}) const;
 
   EntityType entityType() const override;
 
@@ -68,8 +68,8 @@ public:
 
   virtual String description() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint) override;
   void disableInterpolation() override;
diff --git a/source/game/StarPlantDrop.cpp b/source/game/StarPlantDrop.cpp
index ccb57d8..b41705d 100644
--- a/source/game/StarPlantDrop.cpp
+++ b/source/game/StarPlantDrop.cpp
@@ -86,11 +86,12 @@ PlantDrop::PlantDrop(List<Plant::PlantPiece> pieces, Vec2F const& position, Vec2
     m_collisionRect = fullBounds;
 }
 
-PlantDrop::PlantDrop(ByteArray const& netStore) {
+PlantDrop::PlantDrop(ByteArray const& netStore, NetCompatibilityRules rules) {
   m_netGroup.addNetElement(&m_movementController);
   m_netGroup.addNetElement(&m_spawnedDrops);
 
   DataStreamBuffer ds(netStore);
+  ds.setStreamCompatibilityVersion(rules);
   ds >> m_time;
   ds >> m_master;
   ds >> m_description;
@@ -113,7 +114,7 @@ PlantDrop::PlantDrop(ByteArray const& netStore) {
   m_spawnedDropEffects = true;
 }
 
-ByteArray PlantDrop::netStore() {
+ByteArray PlantDrop::netStore(NetCompatibilityRules rules) {
   DataStreamBuffer ds;
   ds << m_time;
   ds << m_master;
@@ -358,12 +359,12 @@ void PlantDrop::render(RenderCallback* renderCallback) {
   }
 }
 
-pair<ByteArray, uint64_t> PlantDrop::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> PlantDrop::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void PlantDrop::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void PlantDrop::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void PlantDrop::enableInterpolation(float extrapolationHint) {
diff --git a/source/game/StarPlantDrop.hpp b/source/game/StarPlantDrop.hpp
index 1b630f4..7528e5d 100644
--- a/source/game/StarPlantDrop.hpp
+++ b/source/game/StarPlantDrop.hpp
@@ -15,9 +15,9 @@ public:
   PlantDrop(List<Plant::PlantPiece> pieces, Vec2F const& position, Vec2F const& strikeVector, String const& description,
       bool upsideDown, Json stemConfig, Json foliageConfig, Json saplingConfig,
       bool master, float random);
-  PlantDrop(ByteArray const& netStore);
+  PlantDrop(ByteArray const& netStore, NetCompatibilityRules rules = {});
 
-  ByteArray netStore();
+  ByteArray netStore(NetCompatibilityRules rules = {});
 
   EntityType entityType() const override;
 
@@ -26,8 +26,8 @@ public:
 
   String description() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint = 0.0f) override;
   void disableInterpolation() override;
diff --git a/source/game/StarPlayer.cpp b/source/game/StarPlayer.cpp
index 9c9c482..8ee6d7a 100644
--- a/source/game/StarPlayer.cpp
+++ b/source/game/StarPlayer.cpp
@@ -187,8 +187,9 @@ Player::Player(PlayerConfigPtr config, Uuid uuid) {
   m_netGroup.setNeedsStoreCallback(bind(&Player::setNetStates, this));
 }
 
-Player::Player(PlayerConfigPtr config, ByteArray const& netStore) : Player(config) {
+Player::Player(PlayerConfigPtr config, ByteArray const& netStore, NetCompatibilityRules rules) : Player(config) {
   DataStreamBuffer ds(netStore);
+  ds.setStreamCompatibilityVersion(rules);
 
   setUniqueId(ds.read<String>());
 
@@ -1618,12 +1619,12 @@ Direction Player::facingDirection() const {
   return m_movementController->facingDirection();
 }
 
-pair<ByteArray, uint64_t> Player::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Player::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Player::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void Player::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void Player::enableInterpolation(float) {
@@ -2319,8 +2320,9 @@ Json Player::diskStore() {
   };
 }
 
-ByteArray Player::netStore() {
+ByteArray Player::netStore(NetCompatibilityRules rules) {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
 
   ds.write(*uniqueId());
   ds.write(m_description);
diff --git a/source/game/StarPlayer.hpp b/source/game/StarPlayer.hpp
index 871ca47..f6e32e0 100644
--- a/source/game/StarPlayer.hpp
+++ b/source/game/StarPlayer.hpp
@@ -76,7 +76,7 @@ public:
   static EnumMap<State> const StateNames;
 
   Player(PlayerConfigPtr config, Uuid uuid = Uuid());
-  Player(PlayerConfigPtr config, ByteArray const& netStore);
+  Player(PlayerConfigPtr config, ByteArray const& netStore, NetCompatibilityRules rules = {});
   Player(PlayerConfigPtr config, Json const& diskStore);
 
   void diskLoad(Json const& diskStore);
@@ -92,7 +92,7 @@ public:
   QuestManagerPtr questManager() const;
 
   Json diskStore();
-  ByteArray netStore();
+  ByteArray netStore(NetCompatibilityRules rules = {});
 
   EntityType entityType() const override;
   ClientEntityMode clientEntityMode() const override;
@@ -118,8 +118,8 @@ public:
   // relative to current position
   RectF collisionArea() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromStep = 0) override;
-  void readNetState(ByteArray data, float interpolationStep = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationStep = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint = 0.0f) override;
   void disableInterpolation() override;
diff --git a/source/game/StarPlayerFactory.cpp b/source/game/StarPlayerFactory.cpp
index f3dbf29..43854b6 100644
--- a/source/game/StarPlayerFactory.cpp
+++ b/source/game/StarPlayerFactory.cpp
@@ -60,8 +60,8 @@ PlayerPtr PlayerFactory::diskLoadPlayer(Json const& diskStore) const {
   return make_shared<Player>(m_config, diskStore);
 }
 
-PlayerPtr PlayerFactory::netLoadPlayer(ByteArray const& netStore) const {
-  return make_shared<Player>(m_config, netStore);
+PlayerPtr PlayerFactory::netLoadPlayer(ByteArray const& netStore, NetCompatibilityRules rules) const {
+  return make_shared<Player>(m_config, netStore, rules);
 }
 
 }
diff --git a/source/game/StarPlayerFactory.hpp b/source/game/StarPlayerFactory.hpp
index a366221..6712b81 100644
--- a/source/game/StarPlayerFactory.hpp
+++ b/source/game/StarPlayerFactory.hpp
@@ -60,7 +60,7 @@ public:
 
   PlayerPtr create() const;
   PlayerPtr diskLoadPlayer(Json const& diskStore) const;
-  PlayerPtr netLoadPlayer(ByteArray const& netStore) const;
+  PlayerPtr netLoadPlayer(ByteArray const& netStore, NetCompatibilityRules rules = {}) const;
 
 private:
   PlayerConfigPtr m_config;
diff --git a/source/game/StarProjectile.cpp b/source/game/StarProjectile.cpp
index 1503f4c..47cb973 100644
--- a/source/game/StarProjectile.cpp
+++ b/source/game/StarProjectile.cpp
@@ -27,7 +27,7 @@ Projectile::Projectile(ProjectileConfigPtr const& config, Json const& parameters
   setup();
 }
 
-Projectile::Projectile(ProjectileConfigPtr const& config, DataStreamBuffer& data) {
+Projectile::Projectile(ProjectileConfigPtr const& config, DataStreamBuffer& data, NetCompatibilityRules rules) {
   m_config = config;
   data.read(m_parameters);
   setup();
@@ -41,8 +41,9 @@ Projectile::Projectile(ProjectileConfigPtr const& config, DataStreamBuffer& data
   setTeam(data.read<EntityDamageTeam>());
 }
 
-ByteArray Projectile::netStore() const {
+ByteArray Projectile::netStore(NetCompatibilityRules rules) const {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
 
   ds.write(m_config->typeName);
   ds.write(m_parameters);
@@ -141,12 +142,12 @@ Vec2F Projectile::velocity() const {
   return m_movementController->velocity();
 }
 
-pair<ByteArray, uint64_t> Projectile::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Projectile::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Projectile::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void Projectile::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void Projectile::enableInterpolation(float extrapolationHint) {
diff --git a/source/game/StarProjectile.hpp b/source/game/StarProjectile.hpp
index 2aec4b4..fdafdbd 100644
--- a/source/game/StarProjectile.hpp
+++ b/source/game/StarProjectile.hpp
@@ -22,9 +22,9 @@ STAR_CLASS(Projectile);
 class Projectile : public virtual Entity, public virtual ScriptedEntity, public virtual PhysicsEntity, public virtual StatusEffectEntity {
 public:
   Projectile(ProjectileConfigPtr const& config, Json const& parameters);
-  Projectile(ProjectileConfigPtr const& config, DataStreamBuffer& netState);
+  Projectile(ProjectileConfigPtr const& config, DataStreamBuffer& netState, NetCompatibilityRules rules = {});
 
-  ByteArray netStore() const;
+  ByteArray netStore(NetCompatibilityRules rules = {}) const;
 
   EntityType entityType() const override;
 
@@ -43,8 +43,8 @@ public:
   ClientEntityMode clientEntityMode() const override;
   bool masterOnly() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint = 0.0f) override;
   void disableInterpolation() override;
diff --git a/source/game/StarProjectileDatabase.cpp b/source/game/StarProjectileDatabase.cpp
index c2a0c26..bb7fbc7 100644
--- a/source/game/StarProjectileDatabase.cpp
+++ b/source/game/StarProjectileDatabase.cpp
@@ -58,10 +58,11 @@ float ProjectileDatabase::gravityMultiplier(String const& type) const {
   return config->movementSettings.getFloat("gravityMultiplier", 1);
 }
 
-ProjectilePtr ProjectileDatabase::netLoadProjectile(ByteArray const& netStore) const {
+ProjectilePtr ProjectileDatabase::netLoadProjectile(ByteArray const& netStore, NetCompatibilityRules rules) const {
   DataStreamBuffer ds(netStore);
+  ds.setStreamCompatibilityVersion(rules);
   String typeName = ds.read<String>();
-  return make_shared<Projectile>(m_configs.get(typeName), ds);
+  return make_shared<Projectile>(m_configs.get(typeName), ds, rules);
 }
 
 ProjectileConfigPtr ProjectileDatabase::readConfig(String const& path) {
diff --git a/source/game/StarProjectileDatabase.hpp b/source/game/StarProjectileDatabase.hpp
index d3cdd3d..dbd7299 100644
--- a/source/game/StarProjectileDatabase.hpp
+++ b/source/game/StarProjectileDatabase.hpp
@@ -111,7 +111,7 @@ public:
   float gravityMultiplier(String const& type) const;
 
   ProjectilePtr createProjectile(String const& type, Json const& parameters = JsonObject()) const;
-  ProjectilePtr netLoadProjectile(ByteArray const& netStore) const;
+  ProjectilePtr netLoadProjectile(ByteArray const& netStore, NetCompatibilityRules rules = {}) const;
 
 private:
   ProjectileConfigPtr readConfig(String const& path);
diff --git a/source/game/StarServerClientContext.cpp b/source/game/StarServerClientContext.cpp
index 838dae0..fcbffbd 100644
--- a/source/game/StarServerClientContext.cpp
+++ b/source/game/StarServerClientContext.cpp
@@ -10,10 +10,11 @@
 
 namespace Star {
 
-ServerClientContext::ServerClientContext(ConnectionId clientId, Maybe<HostAddress> remoteAddress, Uuid playerUuid,
+ServerClientContext::ServerClientContext(ConnectionId clientId, Maybe<HostAddress> remoteAddress, NetCompatibilityRules netRules, Uuid playerUuid,
     String playerName, String playerSpecies, bool canBecomeAdmin, WorldChunks initialShipChunks)
   : m_clientId(clientId),
     m_remoteAddress(remoteAddress),
+    m_netRules(netRules),
     m_playerUuid(playerUuid),
     m_playerName(playerName),
     m_playerSpecies(playerSpecies),
@@ -88,6 +89,10 @@ bool ServerClientContext::canBecomeAdmin() const {
   return m_canBecomeAdmin;
 }
 
+NetCompatibilityRules ServerClientContext::netRules() const {
+  return m_netRules;
+}
+
 String ServerClientContext::descriptiveName() const {
   RecursiveMutexLocker locker(m_mutex);
   String hostName = m_remoteAddress ? toString(*m_remoteAddress) : "local";
@@ -184,7 +189,7 @@ ByteArray ServerClientContext::writeUpdate() {
     shipChunksUpdate = DataStreamBuffer::serialize(take(m_shipChunksUpdate));
 
   ByteArray netGroupUpdate;
-  tie(netGroupUpdate, m_netVersion) = m_netGroup.writeNetState(m_netVersion);
+  tie(netGroupUpdate, m_netVersion) = m_netGroup.writeNetState(m_netVersion, m_netRules);
 
   if (rpcUpdate.empty() && shipChunksUpdate.empty() && netGroupUpdate.empty())
     return {};
diff --git a/source/game/StarServerClientContext.hpp b/source/game/StarServerClientContext.hpp
index 9dbab43..7c54765 100644
--- a/source/game/StarServerClientContext.hpp
+++ b/source/game/StarServerClientContext.hpp
@@ -19,7 +19,7 @@ STAR_CLASS(ServerClientContext);
 
 class ServerClientContext {
 public:
-  ServerClientContext(ConnectionId clientId, Maybe<HostAddress> remoteAddress, Uuid playerUuid,
+  ServerClientContext(ConnectionId clientId, Maybe<HostAddress> remoteAddress, NetCompatibilityRules netRules, Uuid playerUuid,
       String playerName, String playerSpecies, bool canBecomeAdmin, WorldChunks initialShipChunks);
 
   ConnectionId clientId() const;
@@ -28,6 +28,7 @@ public:
   String const& playerName() const;
   String const& playerSpecies() const;
   bool canBecomeAdmin() const;
+  NetCompatibilityRules netRules() const;
   String descriptiveName() const;
 
   // Register additional rpc methods from other server side services.
@@ -87,6 +88,7 @@ public:
 private:
   ConnectionId const m_clientId;
   Maybe<HostAddress> const m_remoteAddress;
+  NetCompatibilityRules m_netRules;
   Uuid const m_playerUuid;
   String const m_playerName;
   String const m_playerSpecies;
diff --git a/source/game/StarSky.cpp b/source/game/StarSky.cpp
index d9ac03a..51e5b73 100644
--- a/source/game/StarSky.cpp
+++ b/source/game/StarSky.cpp
@@ -66,12 +66,12 @@ void Sky::jumpTo(SkyParameters skyParameters) {
   m_skyParametersUpdated = true;
 }
 
-pair<ByteArray, uint64_t> Sky::writeUpdate(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Sky::writeUpdate(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Sky::readUpdate(ByteArray data) {
-  m_netGroup.readNetState(std::move(data));
+void Sky::readUpdate(ByteArray data, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(std::move(data), 0.0f, rules);
 }
 
 void Sky::stateUpdate() {
diff --git a/source/game/StarSky.hpp b/source/game/StarSky.hpp
index 4f6ec0c..6065a9d 100644
--- a/source/game/StarSky.hpp
+++ b/source/game/StarSky.hpp
@@ -30,8 +30,8 @@ public:
 
   void jumpTo(SkyParameters SkyParameters);
 
-  pair<ByteArray, uint64_t> writeUpdate(uint64_t fromVersion = 0);
-  void readUpdate(ByteArray data);
+  pair<ByteArray, uint64_t> writeUpdate(uint64_t fromVersion = 0, NetCompatibilityRules rules = {});
+  void readUpdate(ByteArray data, NetCompatibilityRules rules = {});
   
   // handles flying and warp state transitions
   void stateUpdate();
diff --git a/source/game/StarStagehand.cpp b/source/game/StarStagehand.cpp
index 83b7673..d85f77b 100644
--- a/source/game/StarStagehand.cpp
+++ b/source/game/StarStagehand.cpp
@@ -14,8 +14,7 @@ Stagehand::Stagehand(Json const& config)
   readConfig(config);
 }
 
-Stagehand::Stagehand(ByteArray const& netStore)
-  : Stagehand() {
+Stagehand::Stagehand(ByteArray const& netStore, NetCompatibilityRules rules) : Stagehand() {
   readConfig(DataStreamBuffer::deserialize<Json>(netStore));
 }
 
@@ -31,7 +30,7 @@ Json Stagehand::diskStore() const {
     return saveData.set("scriptStorage", m_scriptComponent.getScriptStorage());
 }
 
-ByteArray Stagehand::netStore() {
+ByteArray Stagehand::netStore(NetCompatibilityRules rules) {
   return DataStreamBuffer::serialize(m_config);
 }
 
@@ -77,12 +76,12 @@ RectF Stagehand::metaBoundBox() const {
   return m_boundBox;
 }
 
-pair<ByteArray, uint64_t> Stagehand::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Stagehand::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Stagehand::readNetState(ByteArray data, float) {
-  m_netGroup.readNetState(std::move(data));
+void Stagehand::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void Stagehand::update(float dt, uint64_t) {
diff --git a/source/game/StarStagehand.hpp b/source/game/StarStagehand.hpp
index 4297370..4403946 100644
--- a/source/game/StarStagehand.hpp
+++ b/source/game/StarStagehand.hpp
@@ -15,10 +15,10 @@ STAR_CLASS(Stagehand);
 class Stagehand : public virtual ScriptedEntity {
 public:
   Stagehand(Json const& config);
-  Stagehand(ByteArray const& netStore);
+  Stagehand(ByteArray const& netStore, NetCompatibilityRules rules = {});
 
   Json diskStore() const;
-  ByteArray netStore();
+  ByteArray netStore(NetCompatibilityRules rules = {});
 
   void init(World* world, EntityId entityId, EntityMode mode) override;
   void uninit() override;
@@ -31,8 +31,8 @@ public:
 
   RectF metaBoundBox() const override;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0) override;
-  void readNetState(ByteArray data, float interpolationTime = 0.0f) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void update(float dt, uint64_t currentStep) override;
 
diff --git a/source/game/StarStatusController.cpp b/source/game/StarStatusController.cpp
index 5a87874..a2a5e9c 100644
--- a/source/game/StarStatusController.cpp
+++ b/source/game/StarStatusController.cpp
@@ -18,7 +18,32 @@ StatusController::StatusController(Json const& config) : m_statCollection(config
   m_parentEntity = nullptr;
   m_movementController = nullptr;
 
-  m_statusProperties.set(config.getObject("statusProperties", {}));
+  m_statusProperties.reset(config.getObject("statusProperties", {}));
+  m_statusProperties.setOverrides(
+    [&](DataStream& ds, NetCompatibilityRules rules) {
+      if (rules.isLegacy) ds << m_statusProperties.baseMap();
+      else m_statusProperties.NetElementHashMap<String, Json>::netStore(ds, rules);
+    },
+    [&](DataStream& ds, NetCompatibilityRules rules) {
+      if (rules.isLegacy) m_statusProperties.reset(ds.read<JsonObject>());
+      else m_statusProperties.NetElementHashMap<String, Json>::netLoad(ds, rules);
+    },
+    [&](DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) {
+      if (rules.isLegacy) {
+        if (m_statusProperties.shouldWriteNetDelta(fromVersion, rules)) {
+          ds << m_statusProperties.baseMap();
+          return true;
+        }
+        return false;
+      }
+      return m_statusProperties.NetElementHashMap<String, Json>::writeNetDelta(ds, fromVersion, rules);
+    },
+    [&](DataStream& ds, float interp, NetCompatibilityRules rules) {
+      if (rules.isLegacy) m_statusProperties.reset(ds.read<JsonObject>());
+      else m_statusProperties.NetElementHashMap<String, Json>::readNetDelta(ds, interp, rules);
+    }
+  );
+
   m_minimumLiquidStatusEffectPercentage = config.getFloat("minimumLiquidStatusEffectPercentage");
   m_appliesEnvironmentStatusEffects = config.getBool("appliesEnvironmentStatusEffects");
   m_appliesWeatherStatusEffects = config.getBool("appliesWeatherStatusEffects");
@@ -72,7 +97,7 @@ Json StatusController::diskStore() const {
   }
 
   return JsonObject{
-      {"statusProperties", m_statusProperties.get()},
+      {"statusProperties", m_statusProperties.baseMap()},
       {"persistentEffectCategories", std::move(persistentEffectCategories)},
       {"ephemeralEffects", std::move(ephemeralEffects)},
       {"resourceValues", std::move(resourceValues)},
@@ -84,7 +109,7 @@ void StatusController::diskLoad(Json const& store) {
   clearAllPersistentEffects();
   clearEphemeralEffects();
 
-  m_statusProperties.set(store.getObject("statusProperties"));
+  m_statusProperties.reset(store.getObject("statusProperties"));
 
   for (auto const& p : store.getObject("persistentEffectCategories", {}))
     addPersistentEffects(p.first, p.second.toArray().transformed(jsonToPersistentStatusEffect));
@@ -103,17 +128,11 @@ void StatusController::diskLoad(Json const& store) {
 }
 
 Json StatusController::statusProperty(String const& name, Json const& def) const {
-  return m_statusProperties.get().value(name, def);
+  return m_statusProperties.value(name, def);
 }
 
 void StatusController::setStatusProperty(String const& name, Json value) {
-  m_statusProperties.update([&](JsonObject& statusProperties) {
-    if (statusProperties[name] != value) {
-      statusProperties[name] = std::move(value);
-      return true;
-    }
-    return false;
-  });
+  m_statusProperties.set(name, value);
 }
 
 StringList StatusController::statNames() const {
@@ -415,15 +434,17 @@ void StatusController::initNetVersion(NetElementVersion const* version) {
   m_netGroup.initNetVersion(version);
 }
 
-void StatusController::netStore(DataStream& ds) const {
-  m_netGroup.netStore(ds);
+void StatusController::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
+  m_netGroup.netStore(ds, rules);
 }
 
-void StatusController::netLoad(DataStream& ds) {
+void StatusController::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   clearAllPersistentEffects();
   clearEphemeralEffects();
 
-  m_netGroup.netLoad(ds);
+  m_netGroup.netLoad(ds, rules);
 }
 
 void StatusController::enableNetInterpolation(float extrapolationHint) {
@@ -438,12 +459,12 @@ void StatusController::tickNetInterpolation(float dt) {
   m_netGroup.tickNetInterpolation(dt);
 }
 
-bool StatusController::writeNetDelta(DataStream& ds, uint64_t fromStep) const {
-  return m_netGroup.writeNetDelta(ds, fromStep);
+bool StatusController::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  return m_netGroup.writeNetDelta(ds, fromVersion, rules);
 }
 
-void StatusController::readNetDelta(DataStream& ds, float interpolationTime) {
-  m_netGroup.readNetDelta(ds, interpolationTime);
+void StatusController::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetDelta(ds, interpolationTime, rules);
 }
 
 void StatusController::blankNetDelta(float interpolationTime) {
@@ -576,15 +597,17 @@ void StatusController::EffectAnimator::initNetVersion(NetElementVersion const* v
   animator.initNetVersion(version);
 }
 
-void StatusController::EffectAnimator::netStore(DataStream& ds) const {
+void StatusController::EffectAnimator::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   ds.write(animationConfig);
-  animator.netStore(ds);
+  animator.netStore(ds, rules);
 }
 
-void StatusController::EffectAnimator::netLoad(DataStream& ds) {
+void StatusController::EffectAnimator::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   ds.read(animationConfig);
   animator = animationConfig ? NetworkedAnimator(*animationConfig) : NetworkedAnimator();
-  animator.netLoad(ds);
+  animator.netLoad(ds, rules);
 }
 
 void StatusController::EffectAnimator::enableNetInterpolation(float extrapolationHint) {
@@ -599,12 +622,12 @@ void StatusController::EffectAnimator::tickNetInterpolation(float dt) {
   animator.tickNetInterpolation(dt);
 }
 
-bool StatusController::EffectAnimator::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
-  return animator.writeNetDelta(ds, fromVersion);
+bool StatusController::EffectAnimator::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  return animator.writeNetDelta(ds, fromVersion, rules);
 }
 
-void StatusController::EffectAnimator::readNetDelta(DataStream& ds, float interpolationTime) {
-  animator.readNetDelta(ds, interpolationTime);
+void StatusController::EffectAnimator::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  animator.readNetDelta(ds, interpolationTime, rules);
 }
 
 void StatusController::EffectAnimator::blankNetDelta(float interpolationTime) {
diff --git a/source/game/StarStatusController.hpp b/source/game/StarStatusController.hpp
index 810a2c9..039cc3b 100644
--- a/source/game/StarStatusController.hpp
+++ b/source/game/StarStatusController.hpp
@@ -2,6 +2,7 @@
 
 #include "StarObserverStream.hpp"
 #include "StarNetElementSystem.hpp"
+#include "StarNetElementExt.hpp"
 #include "StarStatCollection.hpp"
 #include "StarStatusEffectDatabase.hpp"
 #include "StarDamage.hpp"
@@ -103,15 +104,15 @@ public:
 
   void initNetVersion(NetElementVersion const* version = nullptr) override;
 
-  void netStore(DataStream& ds) const override;
-  void netLoad(DataStream& ds) override;
+  void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+  void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
   void enableNetInterpolation(float extrapolationHint = 0.0f) override;
   void disableNetInterpolation() override;
   void tickNetInterpolation(float dt) override;
 
-  bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-  void readNetDelta(DataStream& ds, float interpolationTime = 0.0) override;
+  bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+  void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
   void blankNetDelta(float interpolationTime) override;
 
   void tickMaster(float dt);
@@ -136,15 +137,15 @@ private:
 
     void initNetVersion(NetElementVersion const* version = nullptr) override;
 
-    void netStore(DataStream& ds) const override;
-    void netLoad(DataStream& ds) override;
+    void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+    void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
     void enableNetInterpolation(float extrapolationHint = 0.0f) override;
     void disableNetInterpolation() override;
     void tickNetInterpolation(float dt) override;
 
-    bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-    void readNetDelta(DataStream& ds, float interpolationTime = 0.0) override;
+    bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+    void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
     void blankNetDelta(float interpolationTime) override;
 
     Maybe<String> animationConfig;
@@ -203,7 +204,7 @@ private:
 
   NetElementGroup m_netGroup;
   StatCollection m_statCollection;
-  NetElementData<JsonObject> m_statusProperties;
+  NetElementOverride<NetElementHashMap<String, Json>> m_statusProperties;
   NetElementData<DirectivesGroup> m_parentDirectives;
 
   UniqueEffectMetadataGroup m_uniqueEffectMetadata;
diff --git a/source/game/StarSystemWorld.cpp b/source/game/StarSystemWorld.cpp
index c7e1213..9823b8f 100644
--- a/source/game/StarSystemWorld.cpp
+++ b/source/game/StarSystemWorld.cpp
@@ -453,12 +453,12 @@ void SystemObject::serverUpdate(SystemWorldServer* system, float dt) {
   }
 }
 
-pair<ByteArray, uint64_t> SystemObject::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> SystemObject::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void SystemObject::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void SystemObject::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 ByteArray SystemObject::netStore() const {
@@ -615,12 +615,12 @@ void SystemClientShip::serverUpdate(SystemWorld* system, float dt) {
   }
 }
 
-pair<ByteArray, uint64_t> SystemClientShip::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> SystemClientShip::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void SystemClientShip::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void SystemClientShip::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 ByteArray SystemClientShip::netStore() const {
diff --git a/source/game/StarSystemWorld.hpp b/source/game/StarSystemWorld.hpp
index db12833..cde3323 100644
--- a/source/game/StarSystemWorld.hpp
+++ b/source/game/StarSystemWorld.hpp
@@ -155,8 +155,8 @@ public:
   void clientUpdate(float dt);
   void serverUpdate(SystemWorldServer* system, float dt);
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion);
-  void readNetState(ByteArray data, float interpolationTime);
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion, NetCompatibilityRules rules = {});
+  void readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules = {});
 
   ByteArray netStore() const;
   Json diskStore() const;
@@ -198,8 +198,8 @@ public:
   void clientUpdate(float dt);
   void serverUpdate(SystemWorld* system, float dt);
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion);
-  void readNetState(ByteArray data, float interpolationTime);
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion, NetCompatibilityRules rules = {});
+  void readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules = {});
 
   ByteArray netStore() const;
 private:
diff --git a/source/game/StarSystemWorldServer.cpp b/source/game/StarSystemWorldServer.cpp
index 3b847eb..201b90b 100644
--- a/source/game/StarSystemWorldServer.cpp
+++ b/source/game/StarSystemWorldServer.cpp
@@ -266,7 +266,7 @@ void SystemWorldServer::queueUpdatePackets() {
     HashMap<Uuid, ByteArray> shipUpdates;
     for (auto ship : m_ships.values()) {
       uint64_t version = versions->ships.maybe(ship->uuid()).value(0);
-      auto shipUpdate = ship->writeNetState(version);
+      auto shipUpdate = ship->writeNetState(version, {});
       versions->ships.set(ship->uuid(), shipUpdate.second);
       if (!shipUpdate.first.empty())
         shipUpdates.set(ship->uuid(), shipUpdate.first);
@@ -275,7 +275,7 @@ void SystemWorldServer::queueUpdatePackets() {
     HashMap<Uuid, ByteArray> objectUpdates;
     for (auto object : m_objects.values()) {
       uint64_t version = versions->objects.maybe(object->uuid()).value(0);
-      auto objectUpdate = object->writeNetState(version);
+      auto objectUpdate = object->writeNetState(version, {});
       versions->objects.set(object->uuid(), objectUpdate.second);
       if (!objectUpdate.first.empty())
         objectUpdates.set(object->uuid(), objectUpdate.first);
diff --git a/source/game/StarTechController.cpp b/source/game/StarTechController.cpp
index 90926de..4c0ed55 100644
--- a/source/game/StarTechController.cpp
+++ b/source/game/StarTechController.cpp
@@ -358,15 +358,17 @@ void TechController::TechAnimator::initNetVersion(NetElementVersion const* versi
   netGroup.initNetVersion(version);
 }
 
-void TechController::TechAnimator::netStore(DataStream& ds) const {
+void TechController::TechAnimator::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   ds << animationConfig;
-  netGroup.netStore(ds);
+  netGroup.netStore(ds, rules);
 }
 
-void TechController::TechAnimator::netLoad(DataStream& ds) {
+void TechController::TechAnimator::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   ds >> animationConfig;
   animator = animationConfig ? NetworkedAnimator(*animationConfig) : NetworkedAnimator();
-  netGroup.netLoad(ds);
+  netGroup.netLoad(ds, rules);
 }
 
 void TechController::TechAnimator::enableNetInterpolation(float extrapolationHint) {
@@ -381,12 +383,12 @@ void TechController::TechAnimator::tickNetInterpolation(float dt) {
   netGroup.tickNetInterpolation(dt);
 }
 
-bool TechController::TechAnimator::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
-  return netGroup.writeNetDelta(ds, fromVersion);
+bool TechController::TechAnimator::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  return netGroup.writeNetDelta(ds, fromVersion, rules);
 }
 
-void TechController::TechAnimator::readNetDelta(DataStream& ds, float interpolationTime) {
-  netGroup.readNetDelta(ds, interpolationTime);
+void TechController::TechAnimator::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  netGroup.readNetDelta(ds, interpolationTime, rules);
 }
 
 void TechController::TechAnimator::blankNetDelta(float interpolationTime) {
diff --git a/source/game/StarTechController.hpp b/source/game/StarTechController.hpp
index 3d642df..c399cb5 100644
--- a/source/game/StarTechController.hpp
+++ b/source/game/StarTechController.hpp
@@ -90,15 +90,15 @@ private:
 
     void initNetVersion(NetElementVersion const* version = nullptr) override;
 
-    void netStore(DataStream& ds) const override;
-    void netLoad(DataStream& ds) override;
+    void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+    void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
     void enableNetInterpolation(float extrapolationHint = 0.0f) override;
     void disableNetInterpolation() override;
     void tickNetInterpolation(float dt) override;
 
-    bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-    void readNetDelta(DataStream& ds, float interpolationTime = 0.0) override;
+    bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+    void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
     void blankNetDelta(float interpolationTime) override;
 
     // If setting invisible, stops all playing audio
diff --git a/source/game/StarToolUser.cpp b/source/game/StarToolUser.cpp
index 4135dd0..be239c1 100644
--- a/source/game/StarToolUser.cpp
+++ b/source/game/StarToolUser.cpp
@@ -612,15 +612,17 @@ void ToolUser::NetItem::initNetVersion(NetElementVersion const* version) {
     netItem->initNetVersion(m_netVersion);
 }
 
-void ToolUser::NetItem::netStore(DataStream& ds) const {
+void ToolUser::NetItem::netStore(DataStream& ds, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return;
   const_cast<NetItem*>(this)->updateItemDescriptor();
-  m_itemDescriptor.netStore(ds);
+  m_itemDescriptor.netStore(ds, rules);
   if (auto netItem = as<NetElement>(m_item.get()))
-    netItem->netStore(ds);
+    netItem->netStore(ds, rules);
 }
 
-void ToolUser::NetItem::netLoad(DataStream& ds) {
-  m_itemDescriptor.netLoad(ds);
+void ToolUser::NetItem::netLoad(DataStream& ds, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
+  m_itemDescriptor.netLoad(ds, rules);
 
   auto itemDatabase = Root::singleton().itemDatabase();
   if (itemDatabase->loadItem(m_itemDescriptor.get(), m_item)) {
@@ -633,7 +635,7 @@ void ToolUser::NetItem::netLoad(DataStream& ds) {
   }
 
   if (auto netItem = as<NetElement>(m_item.get()))
-    netItem->netLoad(ds);
+    netItem->netLoad(ds, rules);
 }
 
 void ToolUser::NetItem::enableNetInterpolation(float extrapolationHint) {
@@ -657,23 +659,24 @@ void ToolUser::NetItem::tickNetInterpolation(float dt) {
   }
 }
 
-bool ToolUser::NetItem::writeNetDelta(DataStream& ds, uint64_t fromVersion) const {
+bool ToolUser::NetItem::writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules) const {
+  if (!checkWithRules(rules)) return false;
   bool deltaWritten = false;
   const_cast<NetItem*>(this)->updateItemDescriptor();
   m_buffer.clear();
-  if (m_itemDescriptor.writeNetDelta(m_buffer, fromVersion)) {
+  if (m_itemDescriptor.writeNetDelta(m_buffer, fromVersion, rules)) {
     deltaWritten = true;
     ds.write<uint8_t>(1);
     ds.writeBytes(m_buffer.data());
     if (auto netItem = as<NetElement>(m_item.get())) {
       ds.write<uint8_t>(2);
-      netItem->netStore(ds);
+      netItem->netStore(ds, rules);
     }
   }
 
   if (auto netItem = as<NetElement>(m_item.get())) {
     m_buffer.clear();
-    if (netItem->writeNetDelta(m_buffer, fromVersion)) {
+    if (netItem->writeNetDelta(m_buffer, fromVersion, rules)) {
       deltaWritten = true;
       ds.write<uint8_t>(3);
       ds.writeBytes(m_buffer.data());
@@ -685,13 +688,14 @@ bool ToolUser::NetItem::writeNetDelta(DataStream& ds, uint64_t fromVersion) cons
   return deltaWritten;
 }
 
-void ToolUser::NetItem::readNetDelta(DataStream& ds, float interpolationTime) {
+void ToolUser::NetItem::readNetDelta(DataStream& ds, float interpolationTime, NetCompatibilityRules rules) {
+  if (!checkWithRules(rules)) return;
   while (true) {
     uint8_t code = ds.read<uint8_t>();
     if (code == 0) {
       break;
     } else if (code == 1) {
-      m_itemDescriptor.readNetDelta(ds);
+      m_itemDescriptor.readNetDelta(ds, 0.0f, rules);
       if (!m_item || !m_item->matches(m_itemDescriptor.get(), true)) {
         auto itemDatabase = Root::singleton().itemDatabase();
         if (itemDatabase->loadItem(m_itemDescriptor.get(), m_item)) {
@@ -705,12 +709,12 @@ void ToolUser::NetItem::readNetDelta(DataStream& ds, float interpolationTime) {
       }
     } else if (code == 2) {
       if (auto netItem = as<NetElement>(m_item.get()))
-        netItem->netLoad(ds);
+        netItem->netLoad(ds, rules);
       else
         throw IOException("Server/Client disagreement about whether an Item is a NetElement in NetItem::readNetDelta");
     } else if (code == 3) {
       if (auto netItem = as<NetElement>(m_item.get()))
-        netItem->readNetDelta(ds, interpolationTime);
+        netItem->readNetDelta(ds, interpolationTime, rules);
       else
         throw IOException("Server/Client disagreement about whether an Item is a NetElement in NetItem::readNetDelta");
     } else {
diff --git a/source/game/StarToolUser.hpp b/source/game/StarToolUser.hpp
index 41fe98f..0b954e2 100644
--- a/source/game/StarToolUser.hpp
+++ b/source/game/StarToolUser.hpp
@@ -81,15 +81,15 @@ private:
   public:
     void initNetVersion(NetElementVersion const* version = nullptr) override;
 
-    void netStore(DataStream& ds) const override;
-    void netLoad(DataStream& ds) override;
+    void netStore(DataStream& ds, NetCompatibilityRules rules = {}) const override;
+    void netLoad(DataStream& ds, NetCompatibilityRules rules) override;
 
     void enableNetInterpolation(float extrapolationHint = 0.0f) override;
     void disableNetInterpolation() override;
     void tickNetInterpolation(float dt) override;
 
-    bool writeNetDelta(DataStream& ds, uint64_t fromVersion) const override;
-    void readNetDelta(DataStream& ds, float interpolationTime = 0.0) override;
+    bool writeNetDelta(DataStream& ds, uint64_t fromVersion, NetCompatibilityRules rules = {}) const override;
+    void readNetDelta(DataStream& ds, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
     void blankNetDelta(float interpolationTime) override;
 
     ItemPtr const& get() const;
diff --git a/source/game/StarUniverseClient.cpp b/source/game/StarUniverseClient.cpp
index ed59c4b..023140c 100644
--- a/source/game/StarUniverseClient.cpp
+++ b/source/game/StarUniverseClient.cpp
@@ -94,7 +94,8 @@ Maybe<String> UniverseClient::connect(UniverseConnection connection, bool allowA
   else if (!protocolResponsePacket->allowed)
     return String(strf("Join failed! Server does not support connections with protocol version {}", StarProtocolVersion));
 
-  if (!(m_legacyServer = protocolResponsePacket->compressionMode() != PacketCompressionMode::Enabled)) {
+  bool legacyServer = protocolResponsePacket->compressionMode() != PacketCompressionMode::Enabled;
+  if (!legacyServer) {
     if (auto compressedSocket = as<CompressedPacketSocket>(&connection.packetSocket())) {
       if (protocolResponsePacket->info) {
         auto compressionName = protocolResponsePacket->info.getString("compression", "None");
@@ -104,13 +105,13 @@ Maybe<String> UniverseClient::connect(UniverseConnection connection, bool allowA
 
         Logger::info("UniverseClient: Using '{}' network stream compression", NetCompressionModeNames.getRight(*compressionMode));
         compressedSocket->setCompressionStreamEnabled(compressionMode == NetCompressionMode::Zstd);
-      } else if (!m_legacyServer) {
+      } else {
         Logger::info("UniverseClient: Defaulting to Zstd network stream compression (older server version)");
         compressedSocket->setCompressionStreamEnabled(true);// old OpenSB server version always expects it!
       }
     }
   }
-  connection.packetSocket().setLegacy(m_legacyServer);
+  connection.packetSocket().setLegacy(legacyServer);
   auto clientConnect = make_shared<ClientConnectPacket>(Root::singleton().assets()->digest(), allowAssetsMismatch, m_mainPlayer->uuid(), m_mainPlayer->name(),
       m_mainPlayer->species(), m_playerStorage->loadShipData(m_mainPlayer->uuid()), m_mainPlayer->shipUpgrades(),
       m_mainPlayer->log()->introComplete(), account);
@@ -133,14 +134,18 @@ Maybe<String> UniverseClient::connect(UniverseConnection connection, bool allowA
     packet = connection.pullSingle();
   }
 
+  NetCompatibilityRules compatibilityRules;
+  compatibilityRules.isLegacy = legacyServer;
+
   if (auto success = as<ConnectSuccessPacket>(packet)) {
     m_universeClock = make_shared<Clock>();
     m_clientContext = make_shared<ClientContext>(success->serverUuid, m_mainPlayer->uuid());
+    m_clientContext->setNetCompatibilityRules(compatibilityRules);
     m_teamClient = make_shared<TeamClient>(m_mainPlayer, m_clientContext);
     m_mainPlayer->setClientContext(m_clientContext);
     m_mainPlayer->setStatistics(m_statistics);
     m_worldClient = make_shared<WorldClient>(m_mainPlayer);
-    m_worldClient->clientState().setLegacy(m_legacyServer);
+    m_worldClient->clientState().setNetCompatibilityRules(compatibilityRules);
     m_worldClient->setAsyncLighting(true);
     for (auto& pair : m_luaCallbacks)
       m_worldClient->setLuaCallbacks(pair.first, pair.second);
@@ -149,7 +154,7 @@ Maybe<String> UniverseClient::connect(UniverseConnection connection, bool allowA
     m_celestialDatabase = make_shared<CelestialSlaveDatabase>(std::move(success->celestialInformation));
     m_systemWorldClient = make_shared<SystemWorldClient>(m_universeClock, m_celestialDatabase, m_mainPlayer->universeMap());
 
-    Logger::info("UniverseClient: Joined {} server as client {}", m_legacyServer ? "Starbound" : "OpenStarbound", success->clientId);
+    Logger::info("UniverseClient: Joined {} server as client {}", legacyServer ? "Starbound" : "OpenStarbound", success->clientId);
     return {};
   } else if (auto failure = as<ConnectFailurePacket>(packet)) {
     Logger::error("UniverseClient: Join failed: {}", failure->reason);
@@ -263,7 +268,7 @@ void UniverseClient::update(float dt) {
 
   m_teamClient->update();
 
-  auto contextUpdate = m_clientContext->writeUpdate();
+  auto contextUpdate = m_clientContext->writeUpdate(m_clientContext->netCompatibilityRules());
   if (!contextUpdate.empty())
     m_connection->pushSingle(make_shared<ClientContextUpdatePacket>(std::move(contextUpdate)));
 
@@ -650,7 +655,7 @@ void UniverseClient::handlePackets(List<PacketPtr> const& packets) {
   for (auto const& packet : packets) {
     try {
       if (auto clientContextUpdate = as<ClientContextUpdatePacket>(packet)) {
-        m_clientContext->readUpdate(clientContextUpdate->updateData);
+        m_clientContext->readUpdate(clientContextUpdate->updateData, m_clientContext->netCompatibilityRules());
         m_playerStorage->applyShipUpdates(m_clientContext->playerUuid(), m_clientContext->newShipUpdates());
 
         if (playerIsOriginal())
diff --git a/source/game/StarUniverseClient.hpp b/source/game/StarUniverseClient.hpp
index 985124a..6a85cdb 100644
--- a/source/game/StarUniverseClient.hpp
+++ b/source/game/StarUniverseClient.hpp
@@ -126,7 +126,6 @@ private:
   StatisticsPtr m_statistics;
   PlayerPtr m_mainPlayer;
 
-  bool m_legacyServer;
   bool m_pause;
   ClockPtr m_universeClock;
   WorldClientPtr m_worldClient;
diff --git a/source/game/StarUniverseServer.cpp b/source/game/StarUniverseServer.cpp
index 28f7862..09cfdc8 100644
--- a/source/game/StarUniverseServer.cpp
+++ b/source/game/StarUniverseServer.cpp
@@ -835,7 +835,10 @@ void UniverseServer::warpPlayers() {
           // Checking the spawn target validity then adding the client is not
           // perfect, it can still become invalid in between, if we fail at
           // adding the client we need to warp them back.
-          if (toWorld && toWorld->addClient(clientId, warpToWorld.target, !clientContext->remoteAddress(), clientContext->canBecomeAdmin())) {
+          if (toWorld && toWorld->addClient(clientId, warpToWorld.target,
+            !clientContext->remoteAddress(),
+            clientContext->canBecomeAdmin(),
+            clientContext->netRules())) {
             clientContext->setPlayerWorld(toWorld);
             m_chatProcessor->joinChannel(clientId, printWorldId(warpToWorld.world));
 
@@ -1698,7 +1701,8 @@ void UniverseServer::acceptConnection(UniverseConnection connection, Maybe<HostA
   }
 
   ConnectionId clientId = m_clients.nextId();
-  auto clientContext = make_shared<ServerClientContext>(clientId, remoteAddress, clientConnect->playerUuid,
+  NetCompatibilityRules netRules(legacyClient);
+  auto clientContext = make_shared<ServerClientContext>(clientId, remoteAddress, netRules, clientConnect->playerUuid,
       clientConnect->playerName, clientConnect->playerSpecies, administrator, clientConnect->shipChunks);
   m_clients.add(clientId, clientContext);
   m_connectionServer->addConnection(clientId, std::move(connection));
diff --git a/source/game/StarVehicle.cpp b/source/game/StarVehicle.cpp
index 0aec750..29a57b0 100644
--- a/source/game/StarVehicle.cpp
+++ b/source/game/StarVehicle.cpp
@@ -242,12 +242,12 @@ Vec2F Vehicle::velocity() const {
   return m_movementController.velocity();
 }
 
-pair<ByteArray, uint64_t> Vehicle::writeNetState(uint64_t fromVersion) {
-  return m_netGroup.writeNetState(fromVersion);
+pair<ByteArray, uint64_t> Vehicle::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
-void Vehicle::readNetState(ByteArray data, float interpolationTime) {
-  m_netGroup.readNetState(std::move(data), interpolationTime);
+void Vehicle::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {
+  m_netGroup.readNetState(data, interpolationTime, rules);
 }
 
 void Vehicle::enableInterpolation(float extrapolationHint) {
diff --git a/source/game/StarVehicle.hpp b/source/game/StarVehicle.hpp
index b70d4ae..087137f 100644
--- a/source/game/StarVehicle.hpp
+++ b/source/game/StarVehicle.hpp
@@ -44,8 +44,8 @@ public:
   RectF collisionArea() const override;
   Vec2F velocity() const;
 
-  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion) override;
-  void readNetState(ByteArray data, float interpolationTime = 0) override;
+  pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {}) override;
+  void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {}) override;
 
   void enableInterpolation(float extrapolationHint) override;
   void disableInterpolation() override;
diff --git a/source/game/StarVehicleDatabase.cpp b/source/game/StarVehicleDatabase.cpp
index 370aceb..a8739fa 100644
--- a/source/game/StarVehicleDatabase.cpp
+++ b/source/game/StarVehicleDatabase.cpp
@@ -10,7 +10,7 @@ VehicleDatabase::VehicleDatabase() {
   auto assets = Root::singleton().assets();
   auto& files = assets->scanExtension("vehicle");
   assets->queueJsons(files);
-  for (auto& file : files) {
+  for (String file : files) {
     try {
       auto config = assets->json(file);
       String name = config.getString("name");
@@ -32,15 +32,18 @@ VehiclePtr VehicleDatabase::create(String const& vehicleName, Json const& extraC
   return make_shared<Vehicle>(configPair->second, configPair->first, extraConfig);
 }
 
-ByteArray VehicleDatabase::netStore(VehiclePtr const& vehicle) const {
+ByteArray VehicleDatabase::netStore(VehiclePtr const& vehicle, NetCompatibilityRules rules) const {
   DataStreamBuffer ds;
+  ds.setStreamCompatibilityVersion(rules);
+
   ds.write(vehicle->baseConfig().getString("name"));
   ds.write(vehicle->dynamicConfig());
   return ds.takeData();
 }
 
-VehiclePtr VehicleDatabase::netLoad(ByteArray const& netStore) const {
+VehiclePtr VehicleDatabase::netLoad(ByteArray const& netStore, NetCompatibilityRules rules) const {
   DataStreamBuffer ds(netStore);
+  ds.setStreamCompatibilityVersion(rules);
 
   String name = ds.read<String>();
   auto dynamicConfig = ds.read<Json>();
diff --git a/source/game/StarVehicleDatabase.hpp b/source/game/StarVehicleDatabase.hpp
index ba7bf7c..ed90a7d 100644
--- a/source/game/StarVehicleDatabase.hpp
+++ b/source/game/StarVehicleDatabase.hpp
@@ -13,8 +13,8 @@ public:
 
   VehiclePtr create(String const& vehicleName, Json const& extraConfig = Json()) const;
 
-  ByteArray netStore(VehiclePtr const& vehicle) const;
-  VehiclePtr netLoad(ByteArray const& netStore) const;
+  ByteArray netStore(VehiclePtr const& vehicle, NetCompatibilityRules rules) const;
+  VehiclePtr netLoad(ByteArray const& netStore, NetCompatibilityRules rules) const;
 
   Json diskStore(VehiclePtr const& vehicle) const;
   VehiclePtr diskLoad(Json const& diskStore) const;
diff --git a/source/game/StarWeather.cpp b/source/game/StarWeather.cpp
index 6b1c6a7..6fe1a53 100644
--- a/source/game/StarWeather.cpp
+++ b/source/game/StarWeather.cpp
@@ -55,9 +55,9 @@ void ServerWeather::setClientVisibleRegions(List<RectI> regions) {
   m_clientVisibleRegions = std::move(regions);
 }
 
-pair<ByteArray, uint64_t> ServerWeather::writeUpdate(uint64_t fromVersion) {
+pair<ByteArray, uint64_t> ServerWeather::writeUpdate(uint64_t fromVersion, NetCompatibilityRules rules) {
   setNetStates();
-  return m_netGroup.writeNetState(fromVersion);
+  return m_netGroup.writeNetState(fromVersion, rules);
 }
 
 void ServerWeather::update(double dt) {
@@ -263,9 +263,9 @@ void ClientWeather::setup(WorldGeometry worldGeometry, WeatherEffectsActiveQuery
   m_currentTime = 0.0;
 }
 
-void ClientWeather::readUpdate(ByteArray data) {
+void ClientWeather::readUpdate(ByteArray data, NetCompatibilityRules rules) {
   if (!data.empty()) {
-    m_netGroup.readNetState(std::move(data));
+    m_netGroup.readNetState(data, 0.0f, rules);
     getNetStates();
   }
 }
diff --git a/source/game/StarWeather.hpp b/source/game/StarWeather.hpp
index 7d699ea..4bde334 100644
--- a/source/game/StarWeather.hpp
+++ b/source/game/StarWeather.hpp
@@ -29,7 +29,7 @@ public:
 
   void setClientVisibleRegions(List<RectI> regions);
 
-  pair<ByteArray, uint64_t> writeUpdate(uint64_t fromVersion = 0);
+  pair<ByteArray, uint64_t> writeUpdate(uint64_t fromVersion = 0, NetCompatibilityRules rules = {});
 
   void update(double dt);
 
@@ -80,7 +80,7 @@ public:
 
   void setup(WorldGeometry worldGeometry, WeatherEffectsActiveQuery weatherEffectsActiveQuery);
 
-  void readUpdate(ByteArray data);
+  void readUpdate(ByteArray data, NetCompatibilityRules rules);
 
   void setVisibleRegion(RectI visibleRegion);
 
diff --git a/source/game/StarWorldClient.cpp b/source/game/StarWorldClient.cpp
index 9e0478a..aecb77a 100644
--- a/source/game/StarWorldClient.cpp
+++ b/source/game/StarWorldClient.cpp
@@ -168,7 +168,8 @@ void WorldClient::removeEntity(EntityId entityId, bool andDie) {
   }
 
   if (auto version = m_masterEntitiesNetVersion.maybeTake(entity->entityId())) {
-    ByteArray finalNetState = entity->writeNetState(*version).first;
+    auto netRules = m_clientState.netCompatibilityRules();
+    ByteArray finalNetState = entity->writeNetState(*version, netRules).first;
     m_outgoingPackets.append(make_shared<EntityDestroyPacket>(entity->entityId(), std::move(finalNetState), andDie));
   }
 
@@ -767,7 +768,7 @@ void WorldClient::handleIncomingPackets(List<PacketPtr> const& packets) {
       }
 
       auto entity = entityFactory->netLoadEntity(entityCreate->entityType, entityCreate->storeData);
-      entity->readNetState(entityCreate->firstNetState);
+      entity->readNetState(entityCreate->firstNetState, 0.0f, m_clientState.netCompatibilityRules());
       entity->init(this, entityCreate->entityId, EntityMode::Slave);
       m_entityMap->addEntity(entity);
 
@@ -788,13 +789,13 @@ void WorldClient::handleIncomingPackets(List<PacketPtr> const& packets) {
           EntityId entityId = entity->entityId();
           if (connectionForEntity(entityId) == entityUpdateSet->forConnection) {
             starAssert(entity->isSlave());
-            entity->readNetState(entityUpdateSet->deltas.value(entityId), interpolationLeadTime);
+            entity->readNetState(entityUpdateSet->deltas.value(entityId), interpolationLeadTime, m_clientState.netCompatibilityRules());
           }
         });
 
     } else if (auto entityDestroy = as<EntityDestroyPacket>(packet)) {
       if (auto entity = m_entityMap->entity(entityDestroy->entityId)) {
-        entity->readNetState(entityDestroy->finalNetState, m_interpolationTracker.interpolationLeadTime());
+        entity->readNetState(entityDestroy->finalNetState, m_interpolationTracker.interpolationLeadTime(), m_clientState.netCompatibilityRules());
 
         // Before destroying the entity, we should make sure that the entity is
         // using the absolute latest data, so we disable interpolation.
@@ -909,8 +910,8 @@ void WorldClient::handleIncomingPackets(List<PacketPtr> const& packets) {
       m_interpolationTracker.receiveTimeUpdate(stepUpdate->remoteTime);
 
     } else if (auto environmentUpdatePacket = as<EnvironmentUpdatePacket>(packet)) {
-      m_sky->readUpdate(environmentUpdatePacket->skyDelta);
-      m_weather.readUpdate(environmentUpdatePacket->weatherDelta);
+      m_sky->readUpdate(environmentUpdatePacket->skyDelta, m_clientState.netCompatibilityRules());
+      m_weather.readUpdate(environmentUpdatePacket->weatherDelta, m_clientState.netCompatibilityRules());
 
     } else if (auto hit = as<HitRequestPacket>(packet)) {
       m_damageManager->pushRemoteHitRequest(hit->remoteHitRequest);
@@ -1229,7 +1230,7 @@ void WorldClient::update(float dt) {
 
   queueUpdatePackets(m_entityUpdateTimer.wrapTick(dt));
 
-  if ((!m_clientState.legacy() && m_currentStep % 3 == 0) || m_pingTime.isNothing()) {
+  if ((!m_clientState.netCompatibilityRules().isLegacy && m_currentStep % 3 == 0) || m_pingTime.isNothing()) {
     m_pingTime = Time::monotonicMilliseconds();
     m_outgoingPackets.append(make_shared<PingPacket>(*m_pingTime));
   }
@@ -1325,7 +1326,8 @@ void WorldClient::addEntity(EntityPtr const& entity, EntityId entityId) {
     notifyEntityCreate(entity);
   } else {
     auto entityFactory = Root::singleton().entityFactory();
-    m_outgoingPackets.append(make_shared<SpawnEntityPacket>(entity->entityType(), entityFactory->netStoreEntity(entity), entity->writeNetState().first));
+    auto netRules = m_clientState.netCompatibilityRules();
+    m_outgoingPackets.append(make_shared<SpawnEntityPacket>(entity->entityType(), entityFactory->netStoreEntity(entity), entity->writeNetState(0, netRules).first));
   }
 }
 
@@ -1456,9 +1458,10 @@ void WorldClient::queueUpdatePackets(bool sendEntityUpdates) {
   if (sendEntityUpdates) {
     auto entityUpdateSet = make_shared<EntityUpdateSetPacket>();
     entityUpdateSet->forConnection = *m_clientId;
+    auto netRules = m_clientState.netCompatibilityRules();
     m_entityMap->forAllEntities([&](EntityPtr const& entity) {
         if (auto version = m_masterEntitiesNetVersion.ptr(entity->entityId())) {
-          auto updateAndVersion = entity->writeNetState(*version);
+          auto updateAndVersion = entity->writeNetState(*version, netRules);
           if (!updateAndVersion.first.empty())
             entityUpdateSet->deltas[entity->entityId()] = std::move(updateAndVersion.first);
           *version = updateAndVersion.second;
@@ -1789,13 +1792,13 @@ void WorldClient::initWorld(WorldStartPacket const& startPacket) {
   centerClientWindowOnPlayer();
 
   m_sky = make_shared<Sky>();
-  m_sky->readUpdate(startPacket.skyData);
+  m_sky->readUpdate(startPacket.skyData, m_clientState.netCompatibilityRules());
 
   m_weather.setup(m_geometry, [this](Vec2I const& pos) {
       auto const& tile = m_tileArray->tile(pos);
       return !isRealMaterial(tile.background) && !isSolidColliding(tile.getCollision());
     });
-  m_weather.readUpdate(startPacket.weatherData);
+  m_weather.readUpdate(startPacket.weatherData, m_clientState.netCompatibilityRules());
 
   m_lightingCalculator.setMonochrome(Root::singleton().configuration()->get("monochromeLighting").toBool());
   m_lightingCalculator.setParameters(assets->json("/lighting.config:lighting"));
@@ -1870,7 +1873,8 @@ void WorldClient::tryGiveMainPlayerItem(ItemPtr item, bool silent) {
 void WorldClient::notifyEntityCreate(EntityPtr const& entity) {
   if (entity->isMaster() && !m_masterEntitiesNetVersion.contains(entity->entityId())) {
     // Server was unaware of this entity until now
-    auto firstNetState = entity->writeNetState();
+    auto netRules = m_clientState.netCompatibilityRules();
+    auto firstNetState = entity->writeNetState(0, netRules);
     m_masterEntitiesNetVersion[entity->entityId()] = firstNetState.second;
     m_outgoingPackets.append(make_shared<EntityCreatePacket>(entity->entityType(),
       Root::singleton().entityFactory()->netStoreEntity(entity), std::move(firstNetState.first), entity->entityId()));
diff --git a/source/game/StarWorldClientState.cpp b/source/game/StarWorldClientState.cpp
index 21552cd..4fbefc9 100644
--- a/source/game/StarWorldClientState.cpp
+++ b/source/game/StarWorldClientState.cpp
@@ -22,8 +22,6 @@ WorldClientState::WorldClientState() {
 
   m_netGroup.addNetElement(&m_playerId);
   m_netGroup.addNetElement(&m_clientPresenceEntities);
-
-  m_legacy = false;
 }
 
 RectI WorldClientState::window() const {
@@ -81,20 +79,20 @@ List<RectI> WorldClientState::monitoringRegions(function<Maybe<RectI>(EntityId)>
 
 ByteArray WorldClientState::writeDelta() {
   ByteArray delta;
-  tie(delta, m_netVersion) = m_netGroup.writeNetState(m_netVersion);
+  tie(delta, m_netVersion) = m_netGroup.writeNetState(m_netVersion, m_netCompatibilityRules);
   return delta;
 }
 
 void WorldClientState::readDelta(ByteArray delta) {
-  m_netGroup.readNetState(std::move(delta));
+  m_netGroup.readNetState(std::move(delta), 0.0f, m_netCompatibilityRules);
 }
 
-void WorldClientState::setLegacy(bool legacy) {
-  m_legacy = legacy;
+void WorldClientState::setNetCompatibilityRules(NetCompatibilityRules netCompatibilityRules) {
+  m_netCompatibilityRules = netCompatibilityRules;
 }
 
-bool WorldClientState::legacy() const {
-  return m_legacy;
+NetCompatibilityRules WorldClientState::netCompatibilityRules() const {
+  return m_netCompatibilityRules;
 }
 
 void WorldClientState::reset() {
diff --git a/source/game/StarWorldClientState.hpp b/source/game/StarWorldClientState.hpp
index 920fef4..746b7c5 100644
--- a/source/game/StarWorldClientState.hpp
+++ b/source/game/StarWorldClientState.hpp
@@ -36,9 +36,8 @@ public:
   ByteArray writeDelta();
   void readDelta(ByteArray delta);
 
-  // Whether the client is connected to a legacy server.
-  void setLegacy(bool legacy);
-  bool legacy() const;
+  void setNetCompatibilityRules(NetCompatibilityRules netCompatibilityRules);
+  NetCompatibilityRules netCompatibilityRules() const;
 
   void reset();
 
@@ -57,7 +56,7 @@ private:
   NetElementInt m_playerId;
   NetElementData<List<EntityId>> m_clientPresenceEntities;
 
-  bool m_legacy;
+  NetCompatibilityRules m_netCompatibilityRules;
 };
 
 }
diff --git a/source/game/StarWorldServer.cpp b/source/game/StarWorldServer.cpp
index a78025c..a2df77b 100644
--- a/source/game/StarWorldServer.cpp
+++ b/source/game/StarWorldServer.cpp
@@ -209,7 +209,7 @@ bool WorldServer::spawnTargetValid(SpawnTarget const& spawnTarget) const {
   return true;
 }
 
-bool WorldServer::addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin) {
+bool WorldServer::addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin, NetCompatibilityRules netRules) {
   if (m_clientInfo.contains(clientId))
     return false;
 
@@ -246,6 +246,7 @@ bool WorldServer::addClient(ConnectionId clientId, SpawnTarget const& spawnTarge
   auto& clientInfo = m_clientInfo.add(clientId, make_shared<ClientInfo>(clientId, tracker));
   clientInfo->local = isLocal;
   clientInfo->admin = isAdmin;
+  clientInfo->clientState.setNetCompatibilityRules(netRules);
 
   auto worldStartPacket = make_shared<WorldStartPacket>();
   auto& templateData = worldStartPacket->templateData = m_worldTemplate->store();
@@ -254,8 +255,8 @@ bool WorldServer::addClient(ConnectionId clientId, SpawnTarget const& spawnTarge
     && Root::singletonPtr()->configuration()->getPath("compatibility.customDungeonWorld").optBool().value(false))
     worldStartPacket->templateData = worldStartPacket->templateData.setPath("worldParameters.primaryDungeon", "testarena");
 
-  tie(worldStartPacket->skyData, clientInfo->skyNetVersion) = m_sky->writeUpdate();
-  tie(worldStartPacket->weatherData, clientInfo->weatherNetVersion) = m_weather.writeUpdate();
+  tie(worldStartPacket->skyData, clientInfo->skyNetVersion) = m_sky->writeUpdate(0, netRules);
+  tie(worldStartPacket->weatherData, clientInfo->weatherNetVersion) = m_weather.writeUpdate(0, netRules);
   worldStartPacket->playerStart = playerStart;
   worldStartPacket->playerRespawn = m_playerStart;
   worldStartPacket->respawnInWorld = m_respawnInWorld;
@@ -381,7 +382,7 @@ void WorldServer::handleIncomingPackets(ConnectionId clientId, List<PacketPtr> c
 
     } else if (auto sepacket = as<SpawnEntityPacket>(packet)) {
       auto entity = entityFactory->netLoadEntity(sepacket->entityType, std::move(sepacket->storeData));
-      entity->readNetState(std::move(sepacket->firstNetState));
+      entity->readNetState(std::move(sepacket->firstNetState), 0.0f, clientInfo->clientState.netCompatibilityRules());
       addEntity(std::move(entity));
 
     } else if (auto rdpacket = as<RequestDropPacket>(packet)) {
@@ -434,7 +435,7 @@ void WorldServer::handleIncomingPackets(ConnectionId clientId, List<PacketPtr> c
         }
 
         auto entity = entityFactory->netLoadEntity(entityCreate->entityType, entityCreate->storeData);
-        entity->readNetState(entityCreate->firstNetState);
+        entity->readNetState(entityCreate->firstNetState, 0.0f, clientInfo->clientState.netCompatibilityRules());
         entity->init(this, entityCreate->entityId, EntityMode::Slave);
         m_entityMap->addEntity(entity);
 
@@ -448,14 +449,14 @@ void WorldServer::handleIncomingPackets(ConnectionId clientId, List<PacketPtr> c
           EntityId entityId = entity->entityId();
           if (connectionForEntity(entityId) == clientId) {
             starAssert(entity->isSlave());
-            entity->readNetState(entityUpdateSet->deltas.value(entityId), interpolationLeadTime);
+            entity->readNetState(entityUpdateSet->deltas.value(entityId), interpolationLeadTime, clientInfo->clientState.netCompatibilityRules());
           }
         });
       clientInfo->pendingForward = true;
 
     } else if (auto entityDestroy = as<EntityDestroyPacket>(packet)) {
       if (auto entity = m_entityMap->entity(entityDestroy->entityId)) {
-        entity->readNetState(entityDestroy->finalNetState, clientInfo->interpolationTracker.interpolationLeadTime());
+        entity->readNetState(entityDestroy->finalNetState, clientInfo->interpolationTracker.interpolationLeadTime(), clientInfo->clientState.netCompatibilityRules());
         // Before destroying the entity, we should make sure that the entity is
         // using the absolute latest data, so we disable interpolation.
         entity->disableInterpolation();
@@ -691,6 +692,7 @@ void WorldServer::update(float dt) {
     queueUpdatePackets(pair.first, sendRemoteUpdates);
   }
   m_netStateCache.clear();
+  m_legacyNetStateCache.clear();
 
   for (auto& pair : m_clientInfo)
     pair.second->pendingForward = false;
@@ -1789,10 +1791,10 @@ void WorldServer::queueUpdatePackets(ConnectionId clientId, bool sendRemoteUpdat
 
   if (shouldRunThisStep("environmentUpdate")) {
     ByteArray skyDelta;
-    tie(skyDelta, clientInfo->skyNetVersion) = m_sky->writeUpdate(clientInfo->skyNetVersion);
+    tie(skyDelta, clientInfo->skyNetVersion) = m_sky->writeUpdate(clientInfo->skyNetVersion, clientInfo->clientState.netCompatibilityRules());
 
     ByteArray weatherDelta;
-    tie(weatherDelta, clientInfo->weatherNetVersion) = m_weather.writeUpdate(clientInfo->weatherNetVersion);
+    tie(weatherDelta, clientInfo->weatherNetVersion) = m_weather.writeUpdate(clientInfo->weatherNetVersion, clientInfo->clientState.netCompatibilityRules());
 
     if (!skyDelta.empty() || !weatherDelta.empty())
       clientInfo->outgoingPackets.append(make_shared<EnvironmentUpdatePacket>(std::move(skyDelta), std::move(weatherDelta)));
@@ -1866,12 +1868,14 @@ void WorldServer::queueUpdatePackets(ConnectionId clientId, bool sendRemoteUpdat
     EntityId entityId = monitoredEntity->entityId();
     ConnectionId connectionId = connectionForEntity(entityId);
     if (connectionId != clientId) {
+      auto netRules = clientInfo->clientState.netCompatibilityRules();
       if (auto version = clientInfo->clientSlavesNetVersion.ptr(entityId)) {
         if (auto updateSetPacket = updateSetPackets.value(connectionId)) {
           auto pair = make_pair(entityId, *version);
-          auto i = m_netStateCache.find(pair);
-          if (i == m_netStateCache.end())
-            i = m_netStateCache.insert(pair, monitoredEntity->writeNetState(*version)).first;
+          auto& cache = netRules.isLegacy ? m_legacyNetStateCache : m_netStateCache;
+          auto i = cache.find(pair);
+          if (i == cache.end())
+            i = cache.insert(pair, monitoredEntity->writeNetState(*version, netRules)).first;
           const auto& netState = i->second;
           if (!netState.first.empty())
             updateSetPacket->deltas[entityId] = netState.first;
@@ -1879,7 +1883,7 @@ void WorldServer::queueUpdatePackets(ConnectionId clientId, bool sendRemoteUpdat
         }
       } else if (!monitoredEntity->masterOnly()) {
         // Client was unaware of this entity until now
-        auto firstUpdate = monitoredEntity->writeNetState();
+        auto firstUpdate = monitoredEntity->writeNetState(0, netRules);
         clientInfo->clientSlavesNetVersion.add(entityId, firstUpdate.second);
         clientInfo->outgoingPackets.append(make_shared<EntityCreatePacket>(monitoredEntity->entityType(),
               entityFactory->netStoreEntity(monitoredEntity), std::move(firstUpdate.first), entityId));
@@ -2075,7 +2079,8 @@ void WorldServer::removeEntity(EntityId entityId, bool andDie) {
   for (auto const& pair : m_clientInfo) {
     auto& clientInfo = pair.second;
     if (auto version = clientInfo->clientSlavesNetVersion.maybeTake(entity->entityId())) {
-      ByteArray finalDelta = entity->writeNetState(*version).first;
+      auto netRules = clientInfo->clientState.netCompatibilityRules();
+      ByteArray finalDelta = entity->writeNetState(*version, netRules).first;
       clientInfo->outgoingPackets.append(make_shared<EntityDestroyPacket>(entity->entityId(), std::move(finalDelta), andDie));
     }
   }
diff --git a/source/game/StarWorldServer.hpp b/source/game/StarWorldServer.hpp
index 9e319e5..a87f72d 100644
--- a/source/game/StarWorldServer.hpp
+++ b/source/game/StarWorldServer.hpp
@@ -87,7 +87,7 @@ public:
 
   // Returns false if the client id already exists, or the spawn target is
   // invalid.
-  bool addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin = false);
+  bool addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin = false, NetCompatibilityRules netRules = {});
 
   // Removes client, sends the WorldStopPacket, and returns any pending packets
   // for that client
@@ -375,6 +375,7 @@ private:
   List<CollisionBlock> m_workingCollisionBlocks;
 
   HashMap<pair<EntityId, uint64_t>, pair<ByteArray, uint64_t>> m_netStateCache;
+  HashMap<pair<EntityId, uint64_t>, pair<ByteArray, uint64_t>> m_legacyNetStateCache;
   OrderedHashMap<ConnectionId, shared_ptr<ClientInfo>> m_clientInfo;
 
   GameTimer m_entityUpdateTimer;
diff --git a/source/game/StarWorldServerThread.cpp b/source/game/StarWorldServerThread.cpp
index 1e1f51a..45959ea 100644
--- a/source/game/StarWorldServerThread.cpp
+++ b/source/game/StarWorldServerThread.cpp
@@ -66,10 +66,10 @@ bool WorldServerThread::spawnTargetValid(SpawnTarget const& spawnTarget) {
   }
 }
 
-bool WorldServerThread::addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin) {
+bool WorldServerThread::addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin, NetCompatibilityRules netRules) {
   try {
     RecursiveMutexLocker locker(m_mutex);
-    if (m_worldServer->addClient(clientId, spawnTarget, isLocal, isAdmin)) {
+    if (m_worldServer->addClient(clientId, spawnTarget, isLocal, isAdmin, netRules)) {
       m_clients.add(clientId);
       return true;
     }
diff --git a/source/game/StarWorldServerThread.hpp b/source/game/StarWorldServerThread.hpp
index ae1e666..3223912 100644
--- a/source/game/StarWorldServerThread.hpp
+++ b/source/game/StarWorldServerThread.hpp
@@ -38,7 +38,7 @@ public:
 
   bool spawnTargetValid(SpawnTarget const& spawnTarget);
 
-  bool addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin = false);
+  bool addClient(ConnectionId clientId, SpawnTarget const& spawnTarget, bool isLocal, bool isAdmin = false, NetCompatibilityRules netRules = {});
   // Returns final outgoing packets
   List<PacketPtr> removeClient(ConnectionId clientId);
 
diff --git a/source/game/interfaces/StarActivatableItem.hpp b/source/game/interfaces/StarActivatableItem.hpp
index c8802c0..6501d0b 100644
--- a/source/game/interfaces/StarActivatableItem.hpp
+++ b/source/game/interfaces/StarActivatableItem.hpp
@@ -1,5 +1,4 @@
-#ifndef STAR_ACTIVATABLE_ITEM_HPP
-#define STAR_ACTIVATABLE_ITEM_HPP
+#pragma once
 
 #include "StarConfig.hpp"
 
@@ -16,6 +15,4 @@ public:
   virtual void activate() = 0;
 };
 
-}
-
-#endif
+}
\ No newline at end of file
diff --git a/source/game/interfaces/StarEntity.cpp b/source/game/interfaces/StarEntity.cpp
index cbc968f..150fcbd 100644
--- a/source/game/interfaces/StarEntity.cpp
+++ b/source/game/interfaces/StarEntity.cpp
@@ -1,5 +1,6 @@
 #include "StarEntity.hpp"
 #include "StarDamageManager.hpp"
+#include "StarNetCompatibility.hpp"
 
 namespace Star {
 
@@ -43,11 +44,11 @@ void Entity::uninit() {
   m_entityId = NullEntityId;
 }
 
-pair<ByteArray, uint64_t> Entity::writeNetState(uint64_t) {
+pair<ByteArray, uint64_t> Entity::writeNetState(uint64_t fromVersion, NetCompatibilityRules rules) {
   return {ByteArray(), 0};
 }
 
-void Entity::readNetState(ByteArray, float) {}
+void Entity::readNetState(ByteArray data, float interpolationTime, NetCompatibilityRules rules) {}
 
 void Entity::enableInterpolation(float) {}
 
diff --git a/source/game/interfaces/StarEntity.hpp b/source/game/interfaces/StarEntity.hpp
index 7da2a41..56bd5ac 100644
--- a/source/game/interfaces/StarEntity.hpp
+++ b/source/game/interfaces/StarEntity.hpp
@@ -3,6 +3,7 @@
 #include "StarCasting.hpp"
 #include "StarDamage.hpp"
 #include "StarLightSource.hpp"
+#include "StarDataStream.hpp"
 
 namespace Star {
 
@@ -63,11 +64,11 @@ public:
   // uninitalized.  Should return the delta to be written to the slave, along
   // with the version to pass into writeDeltaState on the next call.  The first
   // delta written to a slave entity will always be the delta starting with 0.
-  virtual pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0);
+  virtual pair<ByteArray, uint64_t> writeNetState(uint64_t fromVersion = 0, NetCompatibilityRules rules = {});
   // Will be called with deltas written by writeDeltaState, including if the
   // delta is empty.  interpolationTime will be provided if interpolation is
   // enabled.
-  virtual void readNetState(ByteArray data, float interpolationTime = 0.0);
+  virtual void readNetState(ByteArray data, float interpolationTime = 0.0f, NetCompatibilityRules rules = {});
 
   virtual void enableInterpolation(float extrapolationHint);
   virtual void disableInterpolation();
diff --git a/source/game/scripting/StarRootLuaBindings.cpp b/source/game/scripting/StarRootLuaBindings.cpp
index 50d18e8..0ce7866 100644
--- a/source/game/scripting/StarRootLuaBindings.cpp
+++ b/source/game/scripting/StarRootLuaBindings.cpp
@@ -237,14 +237,14 @@ LuaCallbacks LuaBindings::makeRootCallbacks() {
 
   
   callbacks.registerCallback("getConfigurationPath", [root](String const& path) -> Json {
-    if (path.beginsWith("title"))
+    if (path.empty() || path.beginsWith("title"))
       throw ConfigurationException(strf("cannot get {}", path));
     else
       return root->configuration()->getPath(path);
     });
 
   callbacks.registerCallback("setConfigurationPath", [root](String const& path, Json const& value) {
-    if (path.beginsWith("safeScripts"))
+    if (path.empty() || path.beginsWith("safeScripts"))
       throw ConfigurationException(strf("cannot set {}", path));
     else
       root->configuration()->setPath(path, value);