Forza Horizon 1: ReImagined

[!TIP]

The launcher is out: latest release

(Linux Flatpak for any distro, Windows installer; both experimental). It builds the game

from your own copy, no build steps needed. Announcement

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The original 2012 Forza Horizon, running natively on PC and rebuilt around the modern Horizon experience: a shared online open world, leaderboards and rivals, high frame rates.

Forza Horizon 1: ReImagined takes Forza Horizon (Xbox 360) and brings it closer to what Horizon is today. The game runs natively on Linux and Windows, made by statically recompiling the original PowerPC executable to C++ with the ReXGlue SDK (the approach of RecompiledHaloReach), and on top of that the project focuses on:

• Better gameplay: 60, 120 or 144 fps with the physics and race timing intact, native

• Online free roam: the Horizon World playlist drops every online player into one

• Leaderboards and rivals: times, ghosts and bounties shared between players, Monthly

• Your own servers: Xbox LIVE and Turn 10's services are long gone, so the project

This repository contains no game code and no game data. You need your own copy of the game (the Games on Demand package or the disc 1 ISO of the base version, Title ID 4D5309C9). The recompiled C++ is generated from your copy on your machine; no binaries are published here.

Contents

• Screenshots
• What works
• Known issues
• Requirements
• Install with the launcher
• Building (Linux)
• Windows
• Playing

• More documentation
• Community
• Legal

Screenshots

Captured from the recompiled game running natively on Linux.

| | | |---|---| | !Free roam
Free roam | !Circuit race
Circuit race against 7 AI drivers | | !Prologue drive
Free roam, Colorado mountains | !Horizon World online
Horizon World online playlist: race lobby and races |

What works

• The whole game, single player: the opening drive to the end of the festival has been

• Title Update 4 (the default), Horizon Rally and the 1000 Club: TU4 is built from your

• All 23 DLC packages: every DLC car counts as installed, the Rally Expansion's 15 and

• Keyboard and mouse or controller: mnk_mode = true plays the menus, free roam, a

• 60, 120 or 144 fps (frame_rate in forza.toml, any rate up to 240), with physics, the

| frame_rate | Free roam | Race, 7 AI cars (Clear Springs Circuit) | |---|---|---| | 60 | 59.9 fps | 59.6 fps | | 120 | 115.2 fps | 75.7 fps | | 144 | 111.5 fps | 70.1 fps |

The race is bound by the GPU emulation above 60; the game itself ran its main loop at the target rate in every run. 0 to 100 km/h takes 2.4 s at every rate.

• Online (through the Forza Live server): sign-in as a Gold member, Find Game and races

• Title Update 4 online (tested with two players on a local server): Horizon World (one

• Your own server: the Forza Live server (server/, Python 3 standard library only, or

Known issues

• The Auction House exists on the server only; its screens were removed from the game, and

• Throttle, brake and steering on the keyboard are all or nothing (the steering has a ramp),

• Races with many AI cars are GPU-bound: 76 fps at a 120 fps target and 70 at 144 (60 holds).
• Windows builds are cross-compiled from Linux and have only been tried under Proton, not

• The launcher (v0.1.0) is experimental: tested end to end on Linux (Flatpak), not yet on Windows.
• Title Update 4 and base-game players can't play together (separate rooms), and a profile

Requirements

• Linux x86-64 or Windows 10/11 64-bit, with a Vulkan 1.3 GPU, about 4 GB of free RAM (measured:

• Your own copy of Forza Horizon, base version: the Games on Demand package

• For the manual build: Clang (tested with 23), CMake >= 3.25, Ninja, Python 3, Git,

• ReXGlue SDK 0.10.0.24 nightly

Install with the launcher

This is the way to install. The launcher builds the game on your machine from your own files; nothing of the game is ever downloaded or shipped.

1. Get the launcher from the latest release:

1. In Setup, point it at your Games on Demand package or your disc 1 ISO (it is

1. Build: it generates the game from your copy and compiles it, downloading a compiler

1. Play. Every setting of forza.toml has a page in Settings (frame rate, display,

Details: docs/launcher.md. The steps below are the same build by hand.

Building (Linux)

# 1. The ReXGlue SDK nightly, unpacked to ~/rexglue-sdk-nightly/0.10.0.24/linux-amd64
2. The game files, extracted from your Games on Demand package (only read)
python3 tools/xcontent_extract.py /path/to/4D5309C9/00007000/<name> extract extracted/game
3. The patched Xenos GPU plugin and codegen tool (clones the SDK to ~/rexglue-sdk-src-forza,
   applies patches/rexglue-sdk/ and installs an overlay at ~/rexglue-sdk-patched-forza;
   the stock rexglue's dot products overflow to infinity, Xenon's to QNaN, and free roam
   crashes without it)
tools/build_rexglue_sdk.sh
4. Configure (the first configure runs codegen with the overlay's rexglue, about a
   minute) and build
cmake -S forza-recomp -B forza-recomp/out/build/linux -G Ninja -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_PREFIX_PATH=$HOME/rexglue-sdk-nightly/0.10.0.24/linux-amd64
ninja -C forza-recomp/out/build/linux

Title Update 4 (needed for Horizon Rally and the 1000 Club; recommended): apply the update to your default.xex (about 2 s; it writes the patched executable, the two facade DLLs and the update's media.zip to extracted/tu4/) and build the TU4 version next to the base one. It has its own hints (hints_tu4/) and generated code (generated_tu4/); a full build is about 4 minutes at -j4 on 8 cores. git checkout forza-recomp/generated/rexglue.cmake afterwards if codegen shows it modified.

python3 tools/apply_title_update.py extracted/game/default.xex /path/to/<title update package or zip> extracted/tu4/default.xex
cmake -S forza-recomp -B forza-recomp/out/build/linux-tu4 -G Ninja -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_PREFIX_PATH=$HOME/rexglue-sdk-nightly/0.10.0.24/linux-amd64 \
  -DFORZA_TITLE_UPDATE=4
ninja -C forza-recomp/out/build/linux-tu4

The launcher does all of this from the two packages (above).

Windows

The Windows version is cross-compiled from Linux with clang/clang-cl and lld-link, after the Linux build above (its codegen output in forza-recomp/generated/ is reused, and step 3 checks out the SDK source). tools/build_windows.sh builds the ReXGlue SDK for Windows from ~/rexglue-sdk-src-forza with this project's patches and the Vulkan backend into ~/rexglue-sdk-patched-forza/0.10.0.24/win-amd64, then the game, and packages it in forza-recomp/out/dist/windows (--sdk-only and --game-only split the long build):

brew install llvm lld                                  # clang, clang-cl, lld-link
xwin --accept-license splat --output ~/.local/opt/xwin/sdk   # MSVC CRT + Windows SDK (Microsoft's license)
tools/build_windows.sh
tools/package_linux.sh                                 # the Linux package, forza-recomp/out/dist/linux

On Windows, extract the package, install the Microsoft Visual C++ 2015-2022 x64 redistributable, extract your game files with python xcontent_extract.py and run play.bat C:\path\to\extracted\game (--offline for no Xbox LIVE; it starts a local Forza Live server when Python is installed, or uses FORZA_SERVER / live_server in forza.toml). Saves, the online identity and the log go to Documents\forza.

Playing

tools/play.sh                 # play with your own profile (~/.local/share/forza)
tools/play.sh --xenia         # continue your Xenia Canary save (a copy)
tools/play.sh --offline       # without Xbox LIVE
tools/play.sh --base          # the base game instead of Title Update 4

play.sh runs the Title Update 4 build (forza-recomp/out/build/linux-tu4) when it exists and the base build otherwise. TU4 converts a profile save when it loads it (ForzaProfile/VersionFlags, a NeedsAA file), and the base build then refuses that profile ("MISSING TITLE UPDATE"): --base is for profiles that never ran on TU4, and a copy of the profile folder lets you go back.

Install DLC once with python3 tools/install_dlc.py /path/to/4D5309C9/00000002 (STFS packages, or a Xenia content folder with the DLC extracted; the launcher's DLC step takes both). Controllers, saves, the Xenia save import and more are in docs/playing.md.

Playing online

play.sh starts a local Forza Live server for the session. To play on the public server, set in forza.toml next to the binary:

live_server = "forza-reimagined.playit.plus:56677"

(or start with FORZA_SERVER=forza-reimagined.playit.plus:56677). You forward no ports. To run your own server, see docs/hosting.md.

More documentation

docs/PROJECT.md (status log, findings, debugging recipes), docs/playing.md, docs/hosting.md, docs/perf.md, docs/framerate.md, and the issue tracker (known bugs and planned work).

Community

Questions, help with setup and online sessions: Discord. Bugs and feature requests: issues (the bug report template asks for your OS, GPU and log).

Legal

Forza Horizon is © Microsoft. This project is not affiliated with, endorsed by or sponsored by Microsoft, Playground Games or Turn 10 Studios. It contains no game code or assets; you must own the game. See LICENSE.