Forza Motorsport 4 Recompiled

An experimental static recompilation of the Xbox 360 version of Forza Motorsport 4 using ReXGlue.

This repository contains project source, recompilation metadata, and build configuration. It does not contain game data, Xbox system files, saves, or compiled executables. You must provide files from your own copy of the game.

The project is licensed under GPL-3.0-only. The license applies only to material this project is entitled to license; it does not grant rights to game files or locally generated translation. See License and content boundary.

Project status

This is an experimental alpha source release. On the tested Windows AMD64 system, the current tree can:

• boot into the game and load an existing profile;
• complete races and save career progress;
• progress from Amateur through Clubman and into the Sportsman tier;
• load the two facade modules used by the game;
• install all four content packages from an extracted Disc 2; and
• render the tested races without the rectangular player shadow, corrupt car materials, or oscillating road brightness.

The validated graphics profile is intentionally conservative. It uses native resolution, the D3D12 ROV path, full resolve readback, synchronous host-copy completion, and the default guest vblank rate. Full readback is expensive, so it can stutter and may run at about 30 FPS even when the host GPU is not fully utilized. Performance and remaining visual issues are still being improved. Higher internal resolution and timing overrides are not considered safe.

Known issues and tested boundary

• Car-thumbnail generation is under investigation. A fresh profile can save a blank thumbnail in which the showroom background is visible but the car is missing; that result can then remain in the profile's thumbnail cache.
• The correctness-oriented full-readback path has substantial, hardware-dependent synchronization cost. Stutter, low host-GPU utilization, and frame rates around 30 FPS are expected on some workloads while this path is improved.

Campaign progression is known good through entry into the Sportsman tier. The campaign beyond that point has not been validated and should not be treated as confirmed working.

See Current status for the tested boundary and known issues.

Requirements

• Windows AMD64
• Git, CMake 3.25 or newer, Ninja, and Clang
• a legally obtained, extracted Forza Motorsport 4 game tree

The current release builder uses the project SDK fork at commit f16992c. That commit contains the validated graphics baseline plus Windows toolchain compatibility work which has not all been accepted upstream. The local builder obtains and builds the exact pinned source automatically.

The project expects these game executables:

extracted/default.xex
extracted/XMediaFacade_default.xex
extracted/SpeechFacade_default.xex

Local build

The supported release path verifies the required Xbox executables, builds the pinned SDK, generates translation on your computer, and builds FM4:

pwsh -File .\tools\Build-Local.ps1 -GameDataRoot "D:\Games\FM4-extracted"
pwsh -File .\tools\Run-Local.ps1 -GameDataRoot "D:\Games\FM4-extracted"

Use -ValidateOnly on the build command to check the dump and toolchain without downloading or building the SDK. Local dependencies, generated code, and build outputs stay under .local; the retained development build is not modified. The run script also isolates profiles, saves, and caches under .local/user.

Developer build

From the repository root:

Push-Location .\fm4
..\sdk\win-amd64\bin\rexglue.exe codegen .\fm4_manifest.toml
cmake --preset win-amd64-release
cmake --build --preset win-amd64-release --parallel 2
Pop-Location

The generated FM4 registrar is unusually large. The build automatically splits it into bounded helper functions so Clang can compile it reliably. Read Build notes before changing function boundaries or the generation pipeline.

Run a completed local build with:

.\Launch FM4.bat

Disc 2 content

Extract the four marketplace-content packages from your own Disc 2 into one directory, then run:

.\Launch FM4 Disc 2 Install.bat "D:\path\to\disc2-packages"

The installer validates each STFS package's title ID and content type before passing it to ReXGlue's content manager. Existing packages are skipped. After installation, normal launches use the copy in user data and no longer require the source directory.

Development notes

• Release notes
• Current status and limitations
• Reusable findings and upstream candidates
• Canonical documentation sources

Repository policy

Do not commit extracted game files, generated source, user data, saves, diagnostic captures, installed SDK files, or compiled binaries. Inspect every staged change before publishing it.

Public artifacts follow the builder-first release process: source and checksums only. The repository does not authorize publishing a precompiled FM4 executable or generated translation.

This project is not affiliated with or endorsed by Microsoft, Xbox, Turn 10 Studios, or the Forza franchise.