What was done
Mercurialuke had Claude Code reverse engineer the save format of Final Fantasy XII The Zodiac Age on PC and write a Windows save editor plus notes on the format.
Mercurialuke published a save editor for Final Fantasy XII The Zodiac Age on PC, along with the notes behind it. He says it is the first public documentation of the PC save format. The AI, Claude via Claude Code, did the reverse engineering and wrote the code and docs.
How it was done
The notes describe the save layout: a header, then data that is zlib compressed and RC4 encrypted, with the key derived through Windows CryptoAPI. The decrypted data is a memory image of the game, so offsets map to the game executable. The notes also name the routines in the game executable that handle settings and the config menu. The author directed the work and tested the results on his own saves in game.
Results
The Windows editor changes gil, characters, jobs, equipment, gambits, licenses, inventory and options. It backs up every save first, re-encodes and compares before writing, reads the file back after writing, and keeps the save checksum and second data copy consistent. Python command-line tools are included. The author warns that key item edits can break quests.