Mega Drive: Sonic 3D

Doctor Robotnik discovered that some strange birds, called Flickies, live on an island in an alternate dimension. He learned that they can travel anywhere using large rings, so he decided to exploit them by turning them into robots to help him search for the Chaos Emeralds. One day, Sonic visited Flickies' Island and saw what Robotnik had done to them. He decided to free the Flickies and stop Robotnik from finding the Emeralds.