Dev used AI agents and more than 500 billion tokens to rebuild Call of Duty: Modern Warfare 2's source code

Developer Maurice Heumann details in his blog how AI agents were able to decompile Call of Duty: Modern Warfare 2 (2009), which the post calls only “a popular first-person shooter,” in an effort to rebuild its source code in C++, taking three months and over 500 billion tokens. The agents originally attempted to cheat a byte-for-byte check added after the first month of code ran, but it was “semantically wrong,” and now 99% of the game’s functions are present, with 83% matching the original.

Heumann’s goal since the beginning has been to produce an “accurate, stable and feature-complete recreation,” and he wrote on X less than two weeks ago that the game was fully playable. By his estimate, the project consumed 600–700 billion tokens. In another X post, he said he doesn’t pay for his own tokens but put the cost at about €1,200 with subscriptions or $200,000–$250,000 with API tokens.

The difficulty turned out to be not in producing …