Sonic comes to life and goes up against such foes as Metal Sonic, the evil hedgehog created by Dr. Robotnik. Sonic must collect all the Time Stones from The Little Planet before Dr. Robotnik can bend time and take over the world. Through more than 50 levels, Sonic can travel through time and explore the past, the present, and the future. And as a special bonus for this enhanced 2011 version of Sonic CD, fans can unlock Tails as a playable character!