Sonic the Hedgehog 2

Story

The South Island has been peaceful since Dr. Robotnik's defeat. Sonic is bored and decides to go on a journey in search of other adventures. When he returns, he is shocked to find the island almost deserted. The only clue as to where all his friends might have disappeared to is Tails, who is being hunted by Dr. Robotnik. Sonic chases after him, but he is too late to save Tails. Sonic finds out that he has been kidnapped by Dr. Robotnik and is being held at a place called Crystal Egg. The price for Tails' safe return is the 6 Chaos Emeralds, which are to be delivered to 6 new boss robots. So Sonic sets off in search of the Chaos Emeralds to rescue Tails.