OVA sonic

Unlike other Sonic the Hedgehog media, the setting of the series is in the world of Planet Freedom, which is split into two distinct realms: the Land of the Sky and the Land of Darkness. The Land of the Sky consists of an unknown number of continents that drift high in the stratosphere of the planet, all of them connected to a massive ice formation which also serves to anchor them to the planet's surface below. According to Knuckles, if this ice network was destroyed, Planet Freedom's rotation would hurl the Land of the Sky into outer space, killing everyone on it. The Land of Darkness is the actual surface of Planet Freedom, a post-apocalyptic wilderness with the dastardly Ivo Robotnik as its sole living inhabitant. The Land of Darkness can only be accessed in one of two ways: by a whirlwind-like "portal" in the Land of the Sky, or via a warp zone, an extradimensional link between two points on Planet Freedom. Most of its terrain is untamed and mountainous, but the city ruins called Ancient Relics are the location of Robotnik's empire. The city and terrain strongly imply that Planet Freedom is a post-apocalyptic Earth that was built upon with floating islands, with certain landmarks suggesting that the ruins are those of New York City.