Epic Mickey will feature Disney's mascot doing battle with lesser known characters from the company's history, hell-bent on revenge for being forgotten. As such, the game will take a darker tone; a more 'Steampunk' setting if you will.
US magazine GameInformer has revealed some pretty impressive concept art, featuring Mr. Mouse holding a paintbrush, said to be the main game mechanic - not unlike that of Okami.
Update
More info on what to expect from Epic Mickey have emerged, with rumours of Oswald the Rabbit's return proving true. Oswald runs a forgotten world where the forgotten Disney characters and fairground rides end up, and he wants revenge on Mickey for his continuing popularity. The Mouse of the House will have paintbrushes, erasers, pencils and other artistic utensils at his disposal, each mapped to select Wii remote movements, and he will be designed with a more retro look in mind. Oswald unleashes the Phantom Blot, who then attempts to take over Mickey's world, and through many puzzle, adventure, and exploration elements, Micks sets out to stop him.
Thanks to GoNintendo.