Halo: Combat Evolved for Linux, Windows, Android and the web

This project is a port of the Halo: Combat Evolved decompilation to Linux, Windows, Android and web browsers. The decompilation is of the Xbox build 2342 (cachebeta.exe, SHA-256 4cc87b45f721270392a96f1674ed2b5cd4a7bb4355faeab4531d1cf1884d9520).

<img width="1289" height="995" alt="The game on Linux" src="https://github.com/user-attachments/assets/0d3ad50f-f8b8-46cf-aef8-e3661da2a7d7" />

The port starts from the decompilation of bnunu/halo-1. That project is a fork of punpckhdq/halo.

Download

GitHub Actions builds the game for each commit. These links download the builds of the latest release:

Platform	Release	Debug
Linux	halo-linux-release.zip	halo-linux-debug.zip
Windows	halo-windows-release.zip	halo-windows-debug.zip
Android	halo-android-release.zip	halo-android-debug.zip
Web	halocombatevolved.com (or halo-web-release.zip for your own server)	halo-web-debug.zip

Use the release build to play. The debug build stops at the first failed assertion and writes it to the log. Use the debug build to find and report problems.

The game updates itself. At start-up it looks for a newer release, and asks if you want to install it. Refer to "Updates" in port/linux/README.md. The web site offers each new build when it is out.

Each build of the main branch that passes on all four platforms is a new release, and the web site then plays it. The Releases page keeps the last five releases. If the latest build has a problem, get an older build from that page.

Game data

The port does not include the game data. Download an Xbox disc image (.xiso or .iso) of Halo: Combat Evolved. All versions of the game operate. The maps of the European (PAL) version were made for a slower console. The port changes them to play as the North American (NTSC) maps do, so players of the two versions can play together.

1. Start the game.
2. At the first start, the game asks for the disc image. Select it.
3. The game extracts the maps/ folder. Then the game starts.

On Linux and Windows, the game puts maps/ next to the executable. On Android, copy the disc image to the phone first. The app puts maps/ in its data folder. Refer to port/android/README.md. On the web, the page copies maps/ out of the disc image into the browser's storage for the site; nothing is uploaded. Refer to port/web/README.md.

Platforms

Each platform has its own instructions:

Platform	Instructions
Linux (32-bit x86 executable, OpenGL 4.5, SDL3)	port/linux/README.md
Windows (32-bit x86 executable, OpenGL 4.5, SDL3)	port/windows/README.md
Android (arm64 app, OpenGL ES 3, SDL3)	port/android/README.md
Web (WebAssembly, WebGL 2, SDL3; desktop Chrome, Edge and Firefox)	port/web/README.md

The Linux README also gives the controls, the settings and the multiplayer functions. These are almost the same on all platforms.

Multiplayer

The game can play system link games on a local network and on the internet:

• A system link game can have up to 128 players on up to 128 machines.
• Linux, Windows and Android machines and browsers can play in the same game. On a local network, the native builds play system link; browsers play each other in rooms, over WebRTC (port/web/README.md).
• An invite link, or the server browser, lets a machine join a game on the internet, browsers too: a native build takes a browser's WebRTC (port/linux/README.md, "Browsers"). No server of this project is necessary.
• The netcode is new. Each machine moves its own player at once, and the host makes the decisions for the game. Refer to port/linux/NETCODE.md.

Build the game

You do not need the Xbox SDK. The port supplies the SDK declarations that the game uses. Refer to port/include/xdk.

To build the game:

1. Install Python and ninja.
2. Install the tools for your platform. Refer to the README for the platform.
3. In the root folder of the repository, enter python configure.py.
4. Enter ninja with the target for the platform:

Target	Result
ninja linux	build/linux/halo
ninja windows (on Windows)	build/windows/halo.exe and SDL3.dll
ninja android_apk	port/android/app/build/outputs/apk/debug/app-debug.apk
ninja web	build/web/site/, the web site (python tools/web_serve.py serves it)

If you enter ninja without a target, ninja builds the game for the computer that you use.

tools/ci_build.py makes the same builds as GitHub Actions. For example, enter python tools/ci_build.py linux release.

Build options

Give these options to configure.py:

Option	Result
(none)	A debug build. A failed assertion stops the game.
--release	A release build. The game does not examine assertions, as in the retail game.
--portable	The Linux and Windows builds operate on all x86-64 processors. The Linux build also operates on older distributions and on SteamOS: refer to "Portable build" in port/linux/README.md. Use this option for builds that you give to other persons.
--lto=thin, --lto=off	Less link-time optimization. The link is faster.
--pgo=off	No profile-guided optimization.
--pgo=train	Records a new optimization profile. Refer to "Optimization profiles".
--profile	A profiling build. It records CPU times. Refer to "Profiling builds".
--web-emcc PATH	The Emscripten emcc for ninja web (else the one on the PATH, or ~/emsdk's).

Without --portable, the Linux and Windows builds use all the instructions of the processor that builds them (-march=native). Such a build does not always start on a different computer.

Optimization profiles

The builds use profiles of the game to optimize the code:

• pgo/halo_linux.profdata for Linux and Android.
• pgo/halo_windows.profdata for Windows.

The profiles need clang 22 or later. With an older clang, the builds do not use the profiles.

To record a new profile:

1. Delete the profile.
2. Enter python configure.py --pgo=train.
3. Enter ninja linux or ninja windows.

The build then plays the main menu and the first minute of each campaign level. This procedure continues for approximately 15 minutes. The game data must be in assets/.

Profiling builds

A profiling build records where the game spends its time.

1. Enter python configure.py --profile, then build as usual.
2. Start a recording. Enter profile_record in the console (or the telnet console), or set debug.profile_record = true in config.toml. To record each game of a session, also set debug.profile_record_when = "game".
3. Stop the recording. Enter profile_stop, load another map, or quit.

The game writes numbered .part<n>.json files under profiles/ in its data root and logs their paths. Parts are retained after the recording stops. Logs go to standard error; a Windows release build without standard error writes them to halo.log next to halo.exe.

tools/net_report.py is a helper for developers. Enter python tools/net_report.py <recording.part1.json> to read a recording as tables. The command also writes <recording>.summary.txt, a short text file.

Command	Result
profile_record [seconds]	Starts a recording. With a number of seconds, the recording stops after that time.
profile_stop	Stops the recording.

debug.profile_memory sets the memory of a recording in MB (default 256, from 4 to 1024). A recording has no length limit: the game writes a part each time the memory is full. Refer to "Settings" in port/linux/README.md.

On Android, the files are in /sdcard/Android/data/com.halo.decomp/files/profiles/. Enter adb pull to copy the recording parts to a computer.

A profiling build plays with normal builds. It does not use --pgo=train.