Sonic Heroes is a 3D platformer.[1] While the preceding Sonic Adventure games for the Dreamcast featured elements of action-adventure and exploration, Sonic Heroes focuses on linear platforming and action,[2][3] similar to the Sonic the Hedgehog games for the Sega Genesis.[4] The story is also simpler than those of the Sonic Adventure games. In it, series antagonist Doctor Eggman threatens to use a weapon to destroy the world and sends out legions of robots. Four groups of three characters from the franchise's history separately team up to put a stop to Eggman's plans.[5] The player navigates using one of the teams, who serve as the player characters.[2] The teams include Team Sonic, which consists of series regulars Sonic the Hedgehog, Miles "Tails" Prower, and Knuckles the Echidna; Team Dark, which includes Shadow the Hedgehog and Rouge the Bat from Sonic Adventure 2, and new character E-123 Omega (considered a spiritual successor to E-102 Gamma from Sonic Adventure); Team Rose, which has Amy Rose, Cream the Rabbit from Sonic Advance 2, and Big the Cat from Sonic Adventure; and Team Chaotix, consisting of Espio the Chameleon, Charmy Bee, and Vector the Crocodile from Knuckles' Chaotix.[5] Each team has its own campaign, called a story.[6] Each also represents a different difficulty. Amy's team, for example, is designed for beginners, while Shadow's is aimed at more experienced players.[4]