What was done
Eray reverse engineered how the PS1 game works and had Claude Code write a native DS engine that plays all 125 rooms of disc 1. It runs on a real DSi XL.
re2ds is a native Nintendo DS engine for Resident Evil 2 (PS1, PAL disc 1, Leon). It is not an emulator. Converters turn data from your own disc into DS formats, and a C engine for devkitARM and libnds plays them with the original game's rules, reverse engineered from the PS1 executable. Commits are co-authored by Claude Opus 5.5.
How it was done
The author posted it to r/ReverseEngineering as built with a reverse engineering workflow and Claude Code. The engine includes a bytecode interpreter for the game's room scripts, covering every opcode used on disc 1, plus tank controls, enemy AI, camera cuts, doors, items and the status screen on the lower screen. No game data is in the repository and none may be shared.
Results
It is playable from the opening movie through Leon's disc 1 rooms, with all 125 rooms, pre-rendered backgrounds with depth masks, collision, zombies that chase and grab, shooting and reloading, and sound and music. A photo shows it on a Nintendo DSi XL. The author says it is not finished and asks for help.