In a bleak aftermath of Sonic CD's events, Sonic's attempt to stop Dr. Robotnik's sinister plan fails. Robotnik fuses with Little Planet, gaining control over time and space. Sonic uses Time Stones but is erased from time. He later escapes, but the world is twisted and decaying. Sonic, now known as "Devoid," can't be seen, as anyone who sees him is consumed. Tails suffers a horrific fate. Robotnik rules the universe, and Devoid seeks revenge, haunted by his past and driven to destroy Robotnik.