Sonic the Hedgehog Chaos
Dr. Robotnik has stolen the red Chaos Emerald, causing the other five to become "unhinged" and scattered in a parallel universe. As a result of the instability, the South Island is now sinking into the sea. It's up to Sonic and Tails to find the Chaos Emeralds and restore harmony to the universe, otherwise the innocent inhabitants of the South Island will have to take a long bath.
Story
The story of Sonic Chaos, like most Sonic stories, revolves around Dr. Robotnik and his quest for world domination with the help of the mythical Chaos Emeralds. The emeralds are the source of life force for all living things, but in the hands of the depraved Dr. Robotnik they can become atomic bombs and laser weapons.