"Sonic Heroes" is a 3D platformer. While the preceding "Sonic Adventure" games for the Dreamcast featured elements of action-adventure and exploration, "Sonic Heroes" focuses on linear platforming and action, similar to the "Sonic the Hedgehog" games for the Sega Genesis. 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. The player navigates using one of the teams, who serve as the player characters. 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". Each team has its own campaign, called a story. Each also represents a different difficulty. Amy's team, for example, is designed for beginners, while Shadow's is aimed at more experienced players.