Planet Freedom

 Planet Freedom is the name of the planet that is the setting of Sonic the Hedgehog: The Movie. It is split into two parts: the Land of the Sky and the Land of Darkness.

Inhabitants
The populace of Planet Freedom ranges from anthropomorphic animals to normal human beings, though the term "human" is never used in the film. The planet is also home to a number of strange human animal hybrids. These include Sara, the President's daughter, who appears to have cat-like features, including a tail, semi cat-like behavior, and cat ears. Her father, the President, also has cat ears and resembles a lion.

Regions
Planet Freedom is made up of two different regions referred to as "dimensions", that separates the planet into two different layers; the outer world that is called the Land of the Sky and the inner dimension that is called the Land of Darkness. Within these regions, several cities and other "Zones" can be found.

Land of the Sky
The Land of the Sky is a region made of sky-bound islands and continents located high above the planet's surface, somewhere in the planet's atmosphere. Each of the landmasses in the Land of the Sky are connected to a glacier, which both anchors them to the planet's surface below and joins them, while separating them from the Land of Darkness. Most of the planet's populace resides in the Land of the Sky, with exceptions being Robotnik and his robot hordes. Apparently, long before the movie's plot, an unknown disaster forced the populace into the mountains, where they rebuilt their cities and named the area the Land of the Sky. It also contains South Island.

Beneath the continents lie rivers of magma that spread all over the planet like blood vessels. If the tip of the huge glacier was punctured by an explosion, the magma would rush to the surface and melt all the ice. This would cause the continents to separate from each other and from the gravitational pull of the planet, sending the inhabitants into space.

Land of Darkness
The Land of Darkness is the world underneath the Land of the Sky and is the actual surface of Planet Freedom. Robotropolis can be found here, as well as what appears to be the decaying ruins of a modern-day city.

Long before the start of the story, the residents of Planet Freedom lived on the surface, but their home city was destroyed by a disaster and the inhabitants of the planet were forced away. Finding the mountains of Planet Freedom high enough to reach the planet's atmosphere, the people of Freedom relocated to the mountains and built a city. Meanwhile, the surface became increasingly polluted and dark. In this time, Robotnik took control of a large portion of the destroyed planet, building his laboratory. Because its skies were shrouded by a blanket of smog and the cities were destroyed and decaying, the people of Planet Freedom gave the area its name.