The planet Mobius in the show.
The series takes place on Mobius, the home planet of Sonic and his friends. The Kingdom of Acorn, a kingdom based within the city of Mobotropolis, was at war with an unseen enemy. King Acorn recruited a human scientist named Julian to build war machines to help achieve victory. However, during a peacetime, Julian and his nephew, Snively launched a coup against the kingdom. The King is banished to another dimension called "The Void" and most of the citizens are captured and made into robot slaves. Julian renames himself to Dr. Robotnik and becomes the dictator of Mobius. Mobotropolis is renamed to Robotropolis and becomes a polluted, industrial landscape.
The city of Robotropolis after the overthrow of King Acorn.
