Sonic returns for a second outing on the Game Boy Advance. Once again, Sonic is called upon to save the world from the evil Dr. Eggman. On this occasion, Sonic is joined by friends Tails, Knuckles and Cream and rabbit, the latest addition to the Sonic Advance & ChuChu Rocket team. Each comes with a set of unique moves, allowing you to reach certain areas through-out the levels.
You must complete the game as Sonic to unlock his friends, Tails, Knuckles and Cream. Collecting Chaos Emeralds will transform Sonic into Super Sonic, which is necessary for the final battle with Dr. Eggman. To get the emeralds, you'll need to find special rings hidden in each stage, unlocking the bonus stage.
Completing the bonus stages rewards you with the Chaos Emeralds and other collectibles. You can also collect and raise chaos creatures, and trade them over to Sonic Adventure 2: Battle on Gamecube, using the GBA/GC link cable.