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. Within each level, the player switches between the team's three characters, who each have unique abilities, to overcome obstacles. 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. Sonic Heroes is a 2003 3D platform game in Sega's Sonic the Hedgehog series.