kirklandsig / halo2-decompiled

# Halo 2 Decompilation (work in progress)
Halo 2 Decompilation is an independent preservation and reverse-engineering
project. It studies the retail executable of **Halo 2 for the original Xbox**
and recreates its program logic in human-readable C and C++ through
independent analysis. Each recreated function is checked against the retail
executable: built with the period-correct compiler, it must produce exactly
the same bytes. That check is what makes the recreated code verifiable. A
longer-term research goal is to study how the game's code could run on other
platforms, using game data that each user supplies from their own copy.
Alongside the game's own code, the project also decompiles **Havok**, the
physics library linked into the game, because Halo 2's vehicles, ragdolls and
projectiles have to behave exactly as they do on the Xbox. The executable's
other libraries (the Xbox SDK's, Bink video and so on) are not decompiled; a
port would replace them.
The project is non-commercial and is not affiliated with or endorsed by
Microsoft, Bungie or 343 Industries. **Read LEGAL.md** for the
project's scope, what it does not contain, and its rules for contributions,
and PROVENANCE.md for where its information comes from.
**This is a community-driven decompilation.** It is built in the open by many
people: contributors who claim a range and send pull requests, and maintainers
who review, merge and keep the build honest. Many of the people working on it,
the maintainer included, work alongside AI coding agents such as Claude and
Codex, and every change still has to pass the same byte-for-byte check and
review. Everyone who has helped is credited in
The community.
**Contributors are welcome.** No prior decompilation experience is needed,
only patience and some C. **New here? Start with
docs/START_HERE.md:** the setup checklist, how to claim
a range, and a prompt you can paste into an AI coding agent. Then see
How to help and CONTRIBUTING.md.
## What this repository does not contain
- No Halo 2 game assets: no maps, textures, models, audio or cinematics.
- No game executable (XBE) and no disc image.
- No Microsoft Xbox SDK/XDK: no compiler, libraries or headers.
- No Havok SDK material: no headers, documentation, samples or source. The
 Havok code here is recreated from the retail executable and named by what it
 does.
- No original or leaked Halo 2 source code.
- No leaked symbols, PDBs or linker maps. Names that came from such sources
 through a third-party dataset have been removed from the inventory, and
 names in the source that matched such sources have been renamed; see
 PROVENANCE.md.
- No confidential or internal Microsoft, Bungie or 343 Industries material.
## Requirements
To build or check anything, you must supply any original game files you need
from a copy of Halo 2 that you are legally entitled to use. The project does
not provide game files.
The project does not distribute the Microsoft Xbox SDK/XDK or any proprietary
Microsoft development