Sonic Advance 2

Taking place on an undefined island, Dr. Eggman has again begun kidnapping Animals and turning them into robots so he can build the Dr. Eggman Empire. This time however, he has kidnapped Tails and Knuckles too. Learning of his friends' kidnapping, Sonic rushes off to save them. Along the way, Sonic saves a young rabbit named Cream and her Chao friend, Cheese, from Eggman after defeating his EggHammerTankII. Cream then joins Sonic on his adventure to find her missing mother, Vanilla.

Sonic soon rescues Tails from Eggman too, although Tails has no idea what Eggman is up to, and Tails joins Sonic on his mission. When Sonic finds Knuckles, the echidna has been tricked by Eggman into fighting Sonic. After being defeated and chided by Sonic, Knuckles comes with him to get back at Eggman. The heroes eventually track Eggman to his Egg Utopia space station, which they destroy, and Cream finds Vanilla in the aftermath, unharmed.

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 the Rabbit, the latest addition to the Sonic team. Each comes with a set of unique moves, allowing you to reach certain areas through-out the levels. However, unlike Sonic Advance, you must complete the game as Sonic to unlock the other characters.

Chaos Emeralds and Special Rings litter the stages. To collect the emeralds (transforming Sonic into Super Sonic for the final battle with Dr. Eggman), you must find the special rings hidden in each stage to unlock the bonus stage. Complete the bonus stage and the emerald is yours.

You'll also get the chance to collect and raise chaos, and trade them over to Sonic Adventure 2: Battle on GameCube, through the use of the GBA/GC link cable.