Sonic the Hedgehog Chaos

The inhabitants of South Island are in danger! Dr. Robotnik has stolen all the Chaos Emeralds which kept the power balance. Robotnik has thrown the Emeralds in a parallel universe and is keeping the red one. Sonic and Tails must retreive all the Chaos Emeralds before the destruction of South Island. The Game Gear version is also the first Game Gear game where you can play either Sonic or Tails.