Sonic Adventure DX: Director's Cut
From Sonic Retro
This is the Sonic Community Hacking Guide for the Gamecube version of Sonic Adventure DX.
If you're looking for the much more hackable PC version, go here.
Note that unlike the Dreamcast and PC versions, this game stores data in big endian byte order. You will likely need to use a converter program before and after you edit the files with programs.
Objects
Main Article: SCHG:Sonic Adventure/Object Editing