Evidence at a glance
Based on the linked sources. The author's reported result and independent confirmation are separate checks.
- AI involvement
- Reported models: Claude, Codex. Tools: Visual C++ 7.1, Python, Git Bash. The writeup below describes the work attributed to AI.
- Reported result
- Partial. This is the directory's source-based outcome classification.
- Independent confirmation
- Not reported.
- Human work and limitations
- The project explicitly notes that it is a work in progress and relies on community contributions. AI agents are used as assistants in the decompilation process, but all results are verified by the project's automated check system.
Original sources
What was done
This project aims to recreate the Halo 2 retail Xbox executable in C/C++ through matching decompilation. Contributors use AI coding agents to assist in reversing functions, which must pass a strict byte-for-byte verification against the original retail binary.
The Halo 2 Decompilation project is an independent reverse-engineering effort focused on the retail Xbox executable of Halo 2. The project utilizes a matching decompilation approach, where recreated C and C++ code must compile to the exact binary representation of the original executable using the period-correct compiler (Visual C++ 7.1 from XDK 5849). Because the game was compiled with link-time code generation (LTCG), functions often feature custom calling conventions and cross-file inlining, making the matching process complex. Contributors and maintainers utilize AI coding agents, specifically Claude and Codex, to assist with the decompilation workflow. Every code change is subject to an automated byte-for-byte verification process to ensure accuracy. As of October 2026, 9,490 retail functions have been successfully matched. The project does not include original game assets, proprietary SDK materials, or leaked source code, and requires users to supply their own legally obtained game files for verification.
Reproduce it
1. Install Python dependencies via requirements-dev.txt. 2. Extract the retail XBE from a legally owned Halo 2 disc image using tools/xiso_extract.py. 3. Configure the environment to point to the XDK/SDK files. 4. Run python tools/check.py to perform the byte-for-byte verification.