Mobius is the planet where Sonic and his friends live. They always hung out until the Death Egg crashed into Mobius because of Mecha Sonic, changing it's fantastic landscape view to a dark & evil scene, with thick black clouds passing in the sky, blocking out the sun. Most (if not all) of Mobius' population was wiped out by Mecha Sonic, including Sonic's friends. Just within short hours, things got worse. More than half of Mobius was reduced to a horrifying burning wasteland. Mecha Sonic had six Chaos Emeralds in his grasp. Sonic, who was still alive and had the last Emerald, battled with him but because the Emerald's powers made him stronger, Mecha Sonic defeated him. Beaten, Sonic layed on the ground and watched him transform using the seven Emeralds' powers. That is, until Shadow intervened and warp the Emeralds to the Mushroom Kingdom. Mecha Sonic warped to the Mushroom Kingdom as well. Sonic and Shadow then left Mobius and headed for the Mushroom Kingdom. Mobius may've remained in the state that Mecha Sonic left it in after all three characters left. Mobius is really Neo Green Hill Zone in Sonic Advance, the ground and sky are the same.