This repository is a full decompilation of the Game Boy Advance games Pokémon Ruby and Sapphire. The codebase recreates the original ROM from C source and assembly, producing a byte-identical binary verified against SHA-1 hashes of the retail releases. It covers all game systems: battle engine, overworld field effects, menus, save data, audio (M4A), graphics, and multiplayer link-cable support. The architecture is a single GBA binary with a state-machine-driven game loop built on a task scheduler (gTasks), a sprite/OAM management layer, palette blending, and a custom script engine for events. The build pipeline includes custom tools for converting PNG, WAV, and MIDI files into GBA binary formats (gbagfx, wav2agb, mid2agb) and a preprocessor for character maps and string tables (preproc). The project is actively maintained, with CI/CD via GitHub Actions, and supports multiple languages (English and German) and game revisions. While many functions retain placeholder names (sub_*) from the decompilation process, the code is well-structured and demonstrably accurate to the original ROM behavior. Key reusable components include standalone graphics and audio conversion tools, a fixed-point trigonometric lookup table, flash memory drivers, and the Real-Time Clock (RTC) interface driver. The repository is primarily of interest to retro game developers, ROM hackers, and those studying Pokémon game mechanics.