G-SA1 integrates Sonic Adventure characters into Garry's Mod using libsa1

G-SA1 enables Sonic Adventure characters, including Sonic, Tails, Knuckles, Amy, E-102 Gamma, Big, and Super Sonic, to function within Garry's Mod. The project utilizes libsa1, a library derived from the Sonic Adventure Dreamcast decompilation, to execute the game's original engine, physics, and character code. Users must provide their own US version 1.005 Dreamcast disc image to supply game data, as the repository contains no SEGA assets. The implementation includes character moves, collision detection with map geometry, sound effects, and the original game HUD. Development is documented in the repository, with ExtCan directing design and testing, and Claude (Anthropic) co-authoring the implementation. While a Linux 64-bit module is generated during the build process, it remains untested in-game. The project maintains a session log for debugging and provides various configuration options via the Garry's Mod spawn menu. Recent commits indicate ongoing development of features such as sun shadows and camera behavior, with the codebase passing numerous test programs without requiring withheld native mesh files. See the G-SA1 repository for full documentation.