Mobius

Mobius is the planet that the Sonic the Hedgehog characters are from in SatAM, Adventures of Sonic the Hedgehog, Sonic Underground, and the comics. Mostly anthropomorphs live there. Note that while originally, some of the American storylines also had Sonic games set on Mobius, the original Japanese manuals have always had Sonic living on Earth, and since post-Sonic Adventure games have followed the Japanese storylines in all regions, it's safe to say Sonic has always lived on Earth in the games