Sonic CD

Sonic CD (or Sonic the Hedgehog CD) is a game in the Sonic the Hedgehog series, for the ill-fated Sega CD system. This is a very unique game in the series, as it was developed at the same time as Sonic the Hedgehog 2. Sonic CD has several differences from most sonic games. The first and most obvious is that in this game, Sonic can time travel from the present to the Past and Future of each zone. By changing things in the past, the Future can either become good or bad. This game also marks the first appearance of Amy Rose and Metal Sonic.