Cain is a cross-platform save editor for Diablo II and Project Diablo 2

Cain is a cross-platform save editor for Diablo II, Lord of Destruction, and various mods, including Project Diablo 2. The tool reads and writes character files, PlugY personal stashes, and shared stash formats. It operates by reading game-specific data, such as stats and item bases, directly from the game's pd2data.mpq file at runtime, allowing it to adapt to different seasons or mods without requiring code changes. The editor includes a validation feature that checks edits against game rules and rejects changes that would prevent a save from loading. The project includes a bundled Claude skill, pd2-build-advisor, which can be installed for Claude Code to provide gear and skill advice by analyzing character JSON output. Development of the editor's in-memory edit model, background MPQ table warming, and asynchronous save functionality involved co-authorship with Claude Opus 4.8 and Claude Sonnet 4.6. The source code is available at https://raw.githubusercontent.com/jackmusick/cain/HEAD/README.md.