What was done
Ryan Hood is decompiling Dragon Ball Z: The Legacy of Goku II with Claude and has patched in a second player with their own HUD, damage and experience, playable locally or over lockstep netplay.
LegacyOfHercule is a decompilation of Dragon Ball Z: The Legacy of Goku II (GBA, USA) with one goal: shared-screen co-op. Ryan Hood works on it with Claude, and the commits are co-authored by Claude Opus 5.5. The repository has a CLAUDE.md quick-start and a work log written for Claude sessions.
How it was done
A headless Ghidra project is built with the GBA memory map and functions seeded from branch targets and pointer tables, because Ghidra's own code finder did not work on this ROM. Findings go into a ROM map. The co-op code is C compiled for the GBA's ARM7 CPU into a blob placed after the original ROM, and a patch script rewrites vtable slots to call it. mGBA Lua scripts carry the second player's input.
Results
The patched ROM adds a second player, Hercule by default, with a separate HUD panel, damage and experience, and a button to switch to another party member. With no second pad the game plays as before. A lockstep netplay script keeps two mGBA instances in sync, checks a state hash every second and re-sends a snapshot on desync. A widescreen build on a modified mGBA widens the view as the players separate. Merging Buu's Fury is planned. No ROM data is included.