With the Death Egg destroyed, Sonic heads off to explore new territories alone. However, antagonist Dr. Eggman has survived their last encounter, and has revisited and improved some of his creations from previous games, attempting to get rid of Sonic as the first part of his new grandiose scheme.

With the Death Egg destroyed, Sonic heads off to explore new territories alone. However, antagonist Dr. Eggman has survived their last encounter, and has revisited and improved some of his creations from previous games, attempting to get rid of Sonic as the first part of his new grandiose scheme.