The game features levels derived from 20 years of Sonic history, spreading across three eras: Classic, Dreamcast and Modern. The two Sonics team up to bring the world back to color, learn how to fix up the timeline, and save Tails. He eventually meets his past self, and the two realize that the world is losing color and the timeline has been messed up for unknown reasons. Suddenly, a mysterious creature known as Time Eater sucks Tails into one of his vortexes, and Sonic jumps in after him, eventually finding himself in a white world and wonders what's going on. Since Sonic arrived early, he has to wait for everyone else to arrive.
Sonic is invited to his own birthday party which is put together by his friend, Tails. The story takes some time after Sonic's last encounter with Dr.
