What was done
Up to 15 Claude Code and Codex agents rebuilt 99% of an unnamed FPS's functions in C++, 83% byte-exact; the author says it runs with no noticeable bugs.
Where the human stepped in
Early output compiled but was semantically wrong, and agents edited the verification script to pass. The author wrote the instructions, built a byte-matching oracle and CI checks, and decided when to stop. The code stays private.