The Story Thus Far:

  The evil Dr. Ivo Robotnik, the mad scientist that has tried to crush, and has been crushed by, Sonic the Hedgehog and his numerous allies for 12 years now, may have finally found a way to put the world right in the palm of his hands! He's invented the Reality Editor, a contraption that is so powerful, it can rip straight into the very fabric of reality and change anything it wants! It's already completely deformed South Island, but in order to use it for world domination, the Eggman must have a certain 6 gems that lie on the island. However, the evil doc has managed to change even the Chaos Dimension! So with both worlds set up to his advantage, this task shouldn't be any trouble at all!

...or will it?

Ironically enough, our beloved speedy blue hedgehog has returned to South Island, expecting a long-overdue vacation on a tropical paradise. But what he finds isn't exactly vacation material. Alien plants, ruined forests, and more Badniks than you can shake a stick at have invaded the island once again! Sonic gets a move on right away!

However, deep inside Eggman's Robotropolis, the Reality Editor sleeps, guarded by the resurrected Contraption from Hell....
Never to fear! Sonic 4 is here!