Mobius

Mobius is an earth-like planet largely inhabited by various sentient anthropomorphic animals and other creatures, some of which include prehistoric, mythological and mystical beings alike. Each such groups have different societies. However, most of the planet's population has already been roboticized by Dr. Robotnik. The planet is also host to humans, the only two known specimens being Dr. Robotnik and Snively.
In addition to animals, due to the work of Dr. Robotnik, robots also maintain a dominant presence on the planet. Also, many places on Mobius suffers from heavy pollution and environmental damage as a result of the pollution from Dr. Robotnik's cities and machines. Despite this, the planet still consists mostly of unspoiled nature which most of its native inhabitants live in harmony with. The landscape of Mobius is also very diverse, with the planet's surface including forests, jungles, mountains, rivers, ancient ruins, seas, islands, and even flying landmasses.