Decompiling Nintendo 64 games in 84 days
On August 26, 2026, engineer
Decompiling a Nintendo 64 Game in 84 Days | Chris' Blog
https://blog.chrislewis.au/decompiling-a-nintendo-64-game-in-84-days/
Lewis previously spent 596 days decompiling ' Super Snowboard Kids ,' meaning he achieved this in about one-seventh of the time.
Lewis attributed the rapid completion of the decompilation to the use of large-scale language models (LLMs), but also stated that this was not the only factor. He noted that the AI proved particularly effective in matching standard library code. However, enabling the AI to leverage existing library resources required more advanced prompt engineering, meaning contributions from human experts were essential. He emphasized that this would not have been possible without the significant cooperation from the decompilation community, including
Community expertise was particularly crucial in analyzing IDO 5.3, a proprietary compiler developed by SGI . Because IDO's source code was unavailable and it relied on older SGI hardware, understanding its behavior and making it work on modern hardware was impossible without community-driven reverse engineering and recompilation. In particular, IDO's multi-stage optimization and code generation process meant that even slight changes to the C language code had a significant impact on register allocation, making its unpredictable behavior complicated the AI-based decompilation workflow. Lewis described understanding IDO's behavior as 'closer to art than science.'
The AI agent excelled in areas where publicly available information could be utilized, such as 'matching standard library code' and 'recording the quirks of specific compilers.' In particular, the ' DECOMPILATION_LEARNINGS.md ' file, which recorded IDO's 'quirks,' formed a feedback loop that facilitated learning between agents. Debugging tools like ' N64 Decomp Workbench ' also helped identify the causes of code inconsistencies and distinguish between structural problems and register allocation issues. However, the AI struggled to reproduce IDO's unique output, and the expertise and intuition of the human team were essential to replicate IDO's behavior.
As the top priority after completing the decompilation, Lewis lists improving the 'game documentation.' The goal is to link all functions to C code, but currently, they don't know what every function does, so the planned tasks include 'changing the generated function names to better reflect their content,' 'identifying struct fields whose purpose is unclear,' and 'cleaning up the generated code.' In parallel, the recompilation of Snowboard Kids is also underway, and it seems that many of the same bugs that were fixed during the recompilation of Super Snowboard Kids are being found. Furthermore, Lewis has expressed interest in attempting to port the levels and content of Snowboard Kids to the Super Snowboard Kids engine, and also in decompilating the PlayStation version of ' Snowboard Kids Plus .' Lewis's article concludes with a call for collaborators.
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