Sonic Adventure 2 (ソニックアドベンチャー 2) is a 3D action platformer game developed by Sonic Team and published by Sega, released in 2001 for the Sega Dreamcast and ported to GameCube as Sonic Adventure 2: Battle, it was also ported to PC, PlayStation 3, and Xbox 360 as a downloadable title. The story focuses on two dynamics; "Hero" and "Dark", with three characters in each, one character from one side playing similar to the other. It ended up being one of the last few games released for the Dreamcast before it's eventual demise.
