Okay, I just finished Sonic Unleashed, and I had a thought... What if the Gaia Colossus failed to get Sonic to the surface in time? So here's the idea: After three months of being trapped in the Earth's Core with Chip dead and the Colossus as his home, Sonic is rescued and returned home. However... he's been exposed to the dormant power of Dark Gaia this whole time, and he's not the same... I would play as Sonic, and you could be whoever you want... Tails, Amy, Eggman, or some non in-game character.