An island has appeared in the ocean where Sonic is taking a nap. Soon Doctor Eggman (aka Doctor Robotnik) comes to the island and starts to collect Chaos Emerald shards to power his base.
The game is a 2D platforming game. You can play as Sonic the Hedgehog, who can utilize the spin dash and other various moves. Sonic now has the ability to double-jump, allowing him to access higher platforms. Knuckles can glide through the air and climb walls. You fight Doctor Eggman (aka Doctor Robotnik) at the end of each zone's second act. You must find all of the Chaos Emeralds in the second act of each zone to find Doctor Eggman and win the game.