diff --git a/.github/workflows/build-toolchain.yml b/.github/workflows/build-toolchain.yml
index 86a2877018..216d8d82c6 100644
--- a/.github/workflows/build-toolchain.yml
+++ b/.github/workflows/build-toolchain.yml
@@ -28,9 +28,9 @@ on:
 
 jobs:
   build:
-    name: Preset ${{ inputs.preset }}${{ inputs.tools && '+t' || '' }}${{ inputs.extras && '+e' || '' }}
+    name: ${{ inputs.preset }}${{ inputs.tools && '+t' || '' }}${{ inputs.extras && '+e' || '' }}
     runs-on: windows-2022
-    timeout-minutes: 40
+    timeout-minutes: 20
     steps:
       - name: Checkout Code
         uses: actions/checkout@v4
diff --git a/.github/workflows/check-replays.yml b/.github/workflows/check-replays.yml
new file mode 100644
index 0000000000..7dca0fba61
--- /dev/null
+++ b/.github/workflows/check-replays.yml
@@ -0,0 +1,240 @@
+name: check-replays
+
+permissions:
+  contents: read
+  pull-requests: write
+
+on:
+  workflow_call:
+    inputs:
+      game:
+        required: true
+        type: string
+        description: "Game to check (only GeneralsMD for now)"
+      userdata:
+        required: true
+        type: string
+        description: "Path to folder with replays and maps"
+      preset:
+        required: true
+        type: string
+        description: "CMake preset"
+
+jobs:
+  build:
+    name: ${{ inputs.preset }}
+    runs-on: windows-latest
+    timeout-minutes: 15
+    env:
+      GAME_PATH: C:\GameData
+      GENERALS_PATH: C:\GameData\Generals
+      GENERALSMD_PATH: C:\GameData\GeneralsMD
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+        with:
+          submodules: true
+
+      - name: Download Game Artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.game }}-${{ inputs.preset }}
+          path: build
+
+      - name: Cache Game Data
+        id: cache-gamedata
+        uses: actions/cache@v4
+        with:
+          path: ${{ env.GAME_PATH }}
+          key: gamedata-permanent-cache-v3
+
+      - name: Download Game Data from Cloudflare R2
+        if: ${{ steps.cache-gamedata.outputs.cache-hit != 'true' }}
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.R2_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.R2_SECRET_ACCESS_KEY }}
+          AWS_ENDPOINT_URL: ${{ secrets.R2_ENDPOINT_URL }}
+          EXPECTED_HASH_GENERALS: "37A351AA430199D1F05DEB9E404857DCE7B461A6AC272C5D4A0B5652CDB06372"
+          EXPECTED_HASH_GENERALSMD: "6837FE1E3009A4C239406C39B1598216C0943EE8ED46BB10626767029AC05E21"
+        shell: pwsh
+        run: |
+          # Download trimmed gamedata of both Generals 1.08 and Generals Zero Hour 1.04.
+          # This data cannot be used for playing because it's
+          # missing textures, audio and gui files. But it's enough for replay checking.
+          # It's also encrypted because it's not allowed to distribute these files.
+
+          if (-not $env:AWS_ACCESS_KEY_ID -or -not $env:AWS_SECRET_ACCESS_KEY -or -not $env:AWS_ENDPOINT_URL) {
+              $ok1 = [bool]$env:AWS_ACCESS_KEY_ID
+              $ok2 = [bool]$env:AWS_SECRET_ACCESS_KEY
+              $ok3 = [bool]$env:AWS_ENDPOINT_URL
+              Write-Host "One or more required secrets are not set or are empty. R2_ACCESS_KEY_ID: $ok1, R2_SECRET_ACCESS_KEY: $ok2, R2_ENDPOINT_URL: $ok3"
+              exit 1
+          }
+
+          # Download Generals Game Files
+          # The archive contains these files:
+          # BINKW32.DLL
+          # English.big
+          # INI.big
+          # Maps.big
+          # mss32.dll
+          # W3D.big
+          # Data\Scripts\MultiplayerScripts.scb
+          # Data\Scripts\SkirmishScripts.scb
+
+          Write-Host "Downloading Game Data for Generals" -ForegroundColor Cyan
+          aws s3 cp s3://github-ci/generals108_gamedata_trimmed.7z generals108_gamedata_trimmed.7z --endpoint-url $env:AWS_ENDPOINT_URL
+
+          Write-Host "Verifying File Integrity" -ForegroundColor Cyan
+          $fileHash = (Get-FileHash -Path generals108_gamedata_trimmed.7z -Algorithm SHA256).Hash
+          Write-Host "Downloaded file SHA256: $fileHash"
+          Write-Host "Expected file SHA256: $env:EXPECTED_HASH_GENERALS"
+          if ($fileHash -ne $env:EXPECTED_HASH_GENERALS) {
+              Write-Error "Hash verification failed! File may be corrupted or tampered with."
+              exit 1
+          }
+
+          Write-Host "Extracting Archive" -ForegroundColor Cyan
+          & 7z x generals108_gamedata_trimmed.7z -o$env:GENERALS_PATH
+          Remove-Item generals108_gamedata_trimmed.7z -Verbose
+
+          # Download GeneralsMD (ZH) Game Files
+          # The archive contains these files:
+          # BINKW32.DLL
+          # INIZH.big
+          # MapsZH.big
+          # mss32.dll
+          # W3DZH.big
+          # Data\Scripts\MultiplayerScripts.scb
+          # Data\Scripts\Scripts.ini
+          # Data\Scripts\SkirmishScripts.scb
+
+          Write-Host "Downloading Game Data for GeneralsMD" -ForegroundColor Cyan
+          aws s3 cp s3://github-ci/zerohour104_gamedata_trimmed.7z zerohour104_gamedata_trimmed.7z --endpoint-url $env:AWS_ENDPOINT_URL
+
+          Write-Host "Verifying File Integrity" -ForegroundColor Cyan
+          $fileHash = (Get-FileHash -Path zerohour104_gamedata_trimmed.7z -Algorithm SHA256).Hash
+          Write-Host "Downloaded file SHA256: $fileHash"
+          Write-Host "Expected file SHA256: $env:EXPECTED_HASH_GENERALSMD"
+          if ($fileHash -ne $env:EXPECTED_HASH_GENERALSMD) {
+              Write-Error "Hash verification failed! File may be corrupted or tampered with."
+              exit 1
+          }
+
+          Write-Host "Extracting Archive" -ForegroundColor Cyan
+          & 7z x zerohour104_gamedata_trimmed.7z -o$env:GENERALSMD_PATH
+          Remove-Item zerohour104_gamedata_trimmed.7z -Verbose
+
+      - name: Set Up Game Data
+        shell: pwsh
+        run: |
+          $source = "$env:GAME_PATH\${{ inputs.game }}"
+          $destination = "build"
+          Copy-Item -Path $source\* -Destination $destination -Recurse -Force
+
+      - name: Set Generals InstallPath in Registry
+        shell: pwsh
+        run: |
+          # Zero Hour loads some Generals files and needs this registry key to find the
+          # Generals data files.
+
+          $regPath = "HKCU:\SOFTWARE\Electronic Arts\EA Games\Generals"
+          $installPath = "$env:GENERALS_PATH\"
+
+          # Ensure the key exists
+          if (-not (Test-Path $regPath)) {
+            New-Item -Path $regPath -Force | Out-Null
+          }
+
+          # Set the InstallPath value
+          Set-ItemProperty -Path $regPath -Name InstallPath -Value $installPath -Type String
+          Write-Host "Registry key set: $regPath -> InstallPath = $installPath"
+
+      - name: Move Replays and Maps to User Dir
+        shell: pwsh
+        run: |
+          # These files are expected in the user dir, so we move them here.
+
+          $source = "${{ inputs.userdata }}\Replays"
+          $destination = "$env:USERPROFILE\Documents\Command and Conquer Generals Zero Hour Data\Replays"
+          Write-Host "Move replays to $destination"
+          New-Item -ItemType Directory -Path $destination -Force | Out-Null
+          Move-Item -Path "$source\*" -Destination $destination -Force
+
+          $source = "${{ inputs.userdata }}\Maps"
+          $destination = "$env:USERPROFILE\Documents\Command and Conquer Generals Zero Hour Data\Maps"
+          Write-Host "Move maps to $destination"
+          New-Item -ItemType Directory -Path $destination -Force | Out-Null
+          Move-Item -Path "$source\*" -Destination $destination -Force
+
+      - name: Run Replay Compatibility Tests
+        shell: pwsh
+        run: |
+          $exePath = "build/generalszh.exe"
+          $arguments = "-jobs 4 -headless -replay *.rep"
+          $timeoutSeconds = 10*60
+          $stdoutPath = "stdout.log"
+          $stderrPath = "stderr.log"
+
+          if (-not (Test-Path $exePath)) {
+              Write-Host "ERROR: Executable not found at $exePath"
+              exit 1
+          }
+
+          # Note that the game is a gui application. That means we need to redirect console output to a file
+          # in order to retrieve it.
+          # Clean previous logs
+          Remove-Item $stdoutPath, $stderrPath -ErrorAction SilentlyContinue
+
+          # Start the process
+          Write-Host "Run $exePath $arguments"
+          $process = Start-Process -FilePath $exePath `
+              -ArgumentList $arguments `
+              -RedirectStandardOutput $stdoutPath `
+              -RedirectStandardError $stderrPath `
+              -PassThru
+
+          # Wait with timeout
+          $exited = $process.WaitForExit($timeoutSeconds * 1000)
+
+          if (-not $exited) {
+              Write-Host "ERROR: Process still running after $timeoutSeconds seconds. Killing process..."
+              Stop-Process -Id $process.Id -Force
+          }
+
+          # Read output
+          Write-Host "=== STDOUT ==="
+          Get-Content $stdoutPath
+
+          if ((Test-Path $stderrPath) -and (Get-Item $stderrPath).Length -gt 0) {
+              Write-Host "`n=== STDERR ==="
+              Get-Content $stderrPath
+          }
+
+          if (-not $exited) {
+              exit 1
+          }
+
+          # Check exit code
+          $exitCode = $process.ExitCode
+          
+          # The above doesn't work on all Windows versions. If not, try this: (see https://stackoverflow.com/a/16018287)
+          #$process.HasExited | Out-Null # Needs to be called for the command below to work correctly
+          #$exitCode = $process.GetType().GetField('exitCode', 'NonPublic, Instance').GetValue($process)
+          #Write-Host "exit code $exitCode"
+
+          if ($exitCode -ne 0) {
+              Write-Host "ERROR: Process failed with exit code $exitCode"
+              exit $exitCode
+          }
+
+          Write-Host "Success!"
+
+      - name: Upload Debug Log
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: Replay-Debug-Log-${{ inputs.preset }}
+          path: build/DebugLogFile*.txt
+          retention-days: 30
+          if-no-files-found: ignore
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ed86c978b3..2d0a8efd65 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -41,8 +41,7 @@ jobs:
             generalsmd:
               - 'GeneralsMD/**'
             shared:
-              - '.github/workflows/build-toolchain.yml'
-              - '.github/workflows/ci.yml'
+              - '.github/workflows/**'
               - 'CMakeLists.txt'
               - 'CMakePresets.json'
               - 'cmake/**'
@@ -100,7 +99,9 @@ jobs:
       extras: ${{ matrix.extras }}
     secrets: inherit
 
-  build-generalsmd:
+  # Note build-generalsmd is split into two jobs for vc6 and win32 because replaycheck-generalsmd
+  # only requires the vc6 build and compiling vc6 is much faster than win32
+  build-generalsmd-vc6:
     name: Build GeneralsMD${{ matrix.preset && '' }}
     needs: detect-changes
     if: ${{ github.event_name == 'workflow_dispatch' || needs.detect-changes.outputs.generalsmd == 'true' || needs.detect-changes.outputs.shared == 'true' }}
@@ -116,6 +117,25 @@ jobs:
           - preset: "vc6-debug"
             tools: true
             extras: true
+          - preset: "vc6-releaselog"
+            tools: true
+            extras: true
+      fail-fast: false
+    uses: ./.github/workflows/build-toolchain.yml
+    with:
+      game: "GeneralsMD"
+      preset: ${{ matrix.preset }}
+      tools: ${{ matrix.tools }}
+      extras: ${{ matrix.extras }}
+    secrets: inherit
+
+  build-generalsmd-win32:
+    name: Build GeneralsMD${{ matrix.preset && '' }}
+    needs: detect-changes
+    if: ${{ github.event_name == 'workflow_dispatch' || needs.detect-changes.outputs.generalsmd == 'true' || needs.detect-changes.outputs.shared == 'true' }}
+    strategy:
+      matrix:
+        include:
           - preset: "win32"
             tools: true
             extras: true
@@ -143,3 +163,20 @@ jobs:
       tools: ${{ matrix.tools }}
       extras: ${{ matrix.extras }}
     secrets: inherit
+
+  replaycheck-generalsmd:
+    name: Replay Check GeneralsMD${{ matrix.preset && '' }}
+    needs: build-generalsmd-vc6
+    if: ${{ github.event_name == 'workflow_dispatch' || needs.detect-changes.outputs.generalsmd == 'true' || needs.detect-changes.outputs.shared == 'true' }}
+    strategy:
+      matrix:
+        include:
+          - preset: "vc6+t+e"
+          - preset: "vc6-releaselog+t+e" # optimized build with logging and crashing enabled should be compatible, so we test that here.
+      fail-fast: false
+    uses: ./.github/workflows/check-replays.yml
+    with:
+      game: "GeneralsMD"
+      userdata: "GeneralsReplays/GeneralsZH/1.04"
+      preset: ${{ matrix.preset }}
+    secrets: inherit
diff --git a/.gitignore b/.gitignore
index e5e550b48d..9ae9ce4288 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@
 !.gitignore
 !.gitattributes
 !.github
+!.gitmodules
 
 *.user
 *.ncb
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000..09d4419ccc
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "GeneralsReplays"]
+	path = GeneralsReplays
+	url = https://github.com/TheSuperHackers/GeneralsReplays
diff --git a/CMakePresets.json b/CMakePresets.json
index 51610bf95c..6dd63816a8 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -44,6 +44,15 @@
                 "RTS_BUILD_OPTION_DEBUG": "ON"
             }
         },
+        {
+            "name": "vc6-releaselog",
+            "displayName": "Windows 32bit VC6 Release Logging",
+            "inherits": "vc6",
+            "cacheVariables": {
+                "RTS_DEBUG_LOGGING": "ON",
+                "RTS_DEBUG_CRASHING": "ON"
+            }
+        },
         {
             "name": "default",
             "displayName": "Default Config (don't use directly!)",
@@ -163,6 +172,12 @@
             "displayName": "Build Windows 32bit VC6 Debug",
             "description": "Build Windows 32bit VC6 Debug"
         },
+        {
+            "name": "vc6-releaselog",
+            "configurePreset": "vc6-releaselog",
+            "displayName": "Build Windows 32bit VC6 Release Logging",
+            "description": "Build Windows 32bit VC6 Release Logging"
+        },
         {
             "name": "win32",
             "configurePreset": "win32",
@@ -253,6 +268,19 @@
                 }
             ]
         },
+        {
+            "name": "vc6-releaselog",
+            "steps": [
+                {
+                    "type": "configure",
+                    "name": "vc6-releaselog"
+                },
+                {
+                    "type": "build",
+                    "name": "vc6-releaselog"
+                }
+            ]
+        },
         {
             "name": "win32",
             "steps": [
diff --git a/GeneralsReplays b/GeneralsReplays
new file mode 160000
index 0000000000..af0c61ccdc
--- /dev/null
+++ b/GeneralsReplays
@@ -0,0 +1 @@
+Subproject commit af0c61ccdccbf06750b0ecd2de99fe65842bfc1a
diff --git a/TESTING.md b/TESTING.md
new file mode 100644
index 0000000000..bcfed39142
--- /dev/null
+++ b/TESTING.md
@@ -0,0 +1,14 @@
+# Test Replays
+
+The GeneralsReplays folder contains replays and the required maps that are tested in CI to ensure that the game is retail compatible.
+
+You can also test with these replays locally:
+- Copy the replays into a subfolder in your `%USERPROFILE%/Documents/Command and Conquer Generals Zero Hour Data/Replays` folder.
+- Copy the maps into `%USERPROFILE%/Documents/Command and Conquer Generals Zero Hour Data/Maps`
+- Start the test with this: (copy into a .bat file next to your executable)
+```
+START /B /W generalszh.exe -jobs 4 -headless -replay subfolder/*.rep > replay_check.log
+echo %errorlevel%
+PAUSE
+```
+It will run the game in the background and check that each replay is compatible. You need to use a VC6 build with optimizations and RTS_BUILD_OPTION_DEBUG = OFF, otherwise the game won't be compatible.
\ No newline at end of file