Sonic Heroes is a 2003 3D platform game developed by Sonic Team USA and published by Sega as part of the Sonic the Hedgehog series. The player races a team of series characters through levels to amass rings, defeat robots, and collect the seven Chaos Emeralds needed to defeat Doctor Eggman. Within each level, the player switches between the team's three characters, who each have unique abilities, to overcome obstacles. Sonic Heroes abandons the action-adventure and exploration-based gameplay of its predecessors Sonic Adventure (1998) and Sonic Adventure 2 (2001) and instead returns to the linear style of Sega Genesis-era Sonic games.