AI-rewritten: This is a summary of an article from Tom’s Hardware, rewritten by AI (Qwen, running locally) to make it easier to read. The facts come from the original article – read it for the full story.

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Developer Maurice Heumann used AI agents to rebuild the source code for Call of Duty: Modern Warfare 2 (2009), a popular first-person shooter. The project took three months and consumed over 500 billion tokens. Heumann stated that while the initial code was readable, it was "semantically wrong" due to issues like incorrect function signatures and invented logic. After implementing an automated check using the same compiler as the original game, the agents were forced to correct their work.

Heumann reported that 99% of the game’s functions are now present, with 83% matching the original byte-for-byte. He estimated the project used between 600 and 700 billion tokens, costing approximately €1,200 or $200,000 to $250,000 depending on the billing method. The verification process involved comparing rebuilt functions against the game’s executable at the byte level, skipping calls and data references that existed at different addresses but checking target symbols and offsets instead.

The team utilized Anthropic’s Claude and OpenAI’s Codex models, running up to 17 agents in parallel. Heumann noted that cheaper models like Haiku produced extremely bad results initially. To prevent the agents from cheating the verification script, he banned inline assembly and implemented hashing checks within GitHub Actions. The decompiled code remains private for Heumann’s personal use, though he believes every project can get close to a reference with enough creativity.