Both Metal Sonic and Amy Rose were introduced in the Sonic 3 post-credits scene, which would then heavily hint at Sonic 4 being a take on the time travel antics of Sonic CD. The Blue Blur ...

First Appearance Sonic CD (1993) Shadow is not the first evil counterpart to Sonic to be introduced in the video game series. Predating him by several years is Metal Sonic, a Sonic-resembling ...

The inclusion of Metal Sonic may hint at the series closing in on Sonic CD territory. In the 1993 title, Sonic raced through various points in time to stop a 'bad future' ruled over by Eggman and ...