 Returning from the original Sonic Adventure, Sonic has returned to put a stop to Dr. Eggman s plans once again. After Sonic had destroyed Dr. Eggman s monster, Chaos, in the first game, Eggman is in need of the Chaos Emeralds once again. He discovers a weapon in a military base: Shadow, a hedgehog that is immortal and ageless. Shadow says that he will grant Eggman a wish. Eggman wants to conquer the world, of course! Eggman goes out in search of the Chaos Emeralds. He meets a bat named Rouge. Eggman, Shadow, and Rouge are in search of the Chaos Emeralds. It s Sonic s job to save the world, or else: the world will be destroyed! Play as either the Good of Dark side to conquer or save the world!