CoD2-BRO-Native-Loader

Call of Duty 2: Big Red One - native loader for PC

Play the original Xbox version of Call of Duty 2: Big Red One on PC, on Linux and Windows. You need your own copy of the game: this repository and its releases contain none of the game's code or data.

The loader runs the game's original code directly on your PC's CPU (the Xbox has an x86 CPU too) and replaces the Xbox around it. Parts of the game, such as the renderer and the sound system, already run as rewritten source code. It is not an emulator or a recompilation; see how it works. It is developed with AI; see Made with AI.

Playing

1. Download the archive for your system from the releases: cod_bro-<version>-linux.tar.gz or cod_bro-<version>-windows.zip.
2. Unpack it anywhere and copy your game dump into its assets/ folder.
3. Start cod_bro_launcher. It sets the options and starts the game, and tells you when a new release is out (Update now installs it; nothing is installed unless you click it).

	Linux	Windows
System	x86 (64- or 32-bit), glibc 2.30 or newer	64-bit Windows 10 or 11
Graphics	Vulkan 1.3 with 32-bit drivers (DXVK included)	Vulkan 1.3 through the included DXVK, or else the Direct3D 9 that comes with Windows
Other	32-bit X11/Wayland and PulseAudio/PipeWire libraries (as 32-bit Steam games need)	-

Controls and options are in the README.txt inside the archive. Saves and settings are kept in your user data folder (~/.local/share/cod_bro or %APPDATA%\cod_bro).

Features

• The whole single-player campaign.
• 60 fps (or the game's 30), higher render resolutions, the game's widescreen mode (wider ultrawide experimental), borderless fullscreen, a field of view setting.
• Controllers, and keyboard and mouse with your own key bindings.
• Enhanced graphics and Enhanced sound: optional improvements, each on its own switch, for those who want them; switched off, you get the picture and sound as on the Xbox.
  • Graphics: anti-aliasing, anisotropic filtering, sharpening, colour vibrance, texture detail.
  • Sound: a higher-quality resampler, more voices, reverb, occlusion behind walls, louder close gunfire.
• Multiplayer over System Link on the local network (docs/multiplayer.md); Xbox Live is not available.
• Other releases of the game (the Collector's Edition, the European French/Spanish/Italian disc) are recognised.

Antivirus warnings (Windows)

Some antivirus programs flag cod_bro_launcher.exe and cod_bro_loader.exe as Gen:Variant.Babar.740485. On VirusTotal, for 0.2.0, 8 of 71 engines report this for the launcher and 7 of 71 for the loader. The Linux files show no detections. We believe these are false positives, and we would rather tell you why than have you find out by surprise:

• "Gen:Variant" is a generic match on behaviour, not a known piece of malware.
• The launcher downloads and installs updates. Update now fetches the new release from this repository, checks it against SHA256SUMS.txt, unpacks it with Windows' own tar and replaces the program files in its folder: what malware "downloaders" do too.
• The loader runs another program's code. cod_bro_loader.exe is a tiny program that reserves memory at fixed addresses, loads the original game's code from your dump into it and changes parts of it while it runs. That is how the native loader works, and also what some malware does.
• The files are not code-signed. A signing certificate costs money every year, and this is a free hobby project.

To check for yourself: release 0.2.0 notes link to the VirusTotal results of its files; all source code is in this repository and you can build it yourself (docs/development.md); the checksums are in SHA256SUMS.txt. The launcher is optional: cod_bro_loader.exe runs the game on its own (with settings.ini), and you can update by downloading releases yourself.

The project is developed on Linux, so Windows antivirus warnings like these can slip past us; please report them as an issue when you see one. Thanks to the reporter of issue #15 and to Reddit user GroundbreakingMap719 for bringing this to our attention.

Status

Version 0.2.0 is the last feature release of the native loader: from here it gets bug fixes only. Work continues in the decompilation repository: rewriting the rest of the game, then a native build of our own that needs only the game's assets. Details and next steps: docs/status.md. Problems and questions: issues (attach log.txt from your user data folder).

Made with AI

This project is developed with AI. Most of its code, the reverse engineering of the game (the Ghidra analysis behind every patch and replaced library), the function names, the decompiled game code and its documentation were written by Claude, Anthropic's AI model, working in Claude Code. The evidence for each function name is recorded in tools/data/manual_names.csv, and every rewritten function is checked against the original by the comparison harness before it replaces it. The maintainer directs the work, decides what gets built, playtests the builds, and reviews and publishes the results. Mistakes are the project's own: please report them as issues.

License

The native loader's own code (everything outside third_party/), including the rewritten game code in game/code/, is licensed under the GNU General Public License, version 2 or (at your option) any later version (LICENSE).

The releases bundle these libraries, each under its own license (texts and versions in LICENSES/ inside every archive):

Component	Used for	License
SDL3	Window, controllers, keyboard and mouse	zlib
OpenAL Soft	Sound	LGPL-2.0-or-later (a separate library you can replace)
DXVK	Direct3D 9 on Vulkan	zlib
Dear ImGui	The launcher's interface	MIT
stb_truetype	Drawing fonts for sharper text	MIT / public domain
EB Garamond, Jost, Liberation Serif, Anton (fonts/)	Sharper text: stand-ins for the game's bitmap fonts	SIL Open Font License 1.1 (fonts/README.md)
GCC runtime, mingw-w64 (Windows only)	C/C++ runtime	GPL-3.0 with the GCC runtime library exception; mingw-w64 terms

The third_party/xbox-includes submodule (Xbox kernel and SDK headers; GPL-2.0, CC0 and LGPL-2.1 files) is not compiled into any build. File-by-file details are in LICENSES/README.md.

The game is not included. Call of Duty 2: Big Red One and all of its code and data belong to Activision Publishing, Inc., a subsidiary of Microsoft Corporation, and their respective copyright holders. You need your own legally obtained copy of the game; piracy is illegal. The symbol files, function names and test results in tools/data/ come from our own analysis. This project is not affiliated with or endorsed by Microsoft, Activision or Treyarch. Call of Duty is a trademark of Activision Publishing, Inc.; Xbox is a trademark of Microsoft Corporation.

Documentation

File	Contents
docs/how-it-works.md	How the native loader works; the rewritten renderer
docs/development.md	Building, running, testing, tools, the repository's layout, releases
docs/status.md	What works, playtest results, session notes, next steps
docs/own-renderer.md	Our own renderer and Enhanced graphics
docs/rendering.md	The Direct3D replacement: render scale, widescreen, frame dumps
docs/comparison-harness.md	Checking rewritten functions against the original
docs/multiplayer.md	System Link multiplayer
docs/playtesting.md	--diag sessions, scripted and unattended runs
docs/naming.md, docs/nal_animation.md	How functions get their names; the NAL animation codec
assets/README.md	For players: where the game files go
LICENSES/README.md	Licenses of everything in the repository