During the Epic Mickey event today in London, Warren Spector and Disney announced more details regarding the game, along with the announcement that Oswald the Lucky Rabbit will be the antagonist in the game.
Apparently, the sorcerer Yen Sid (from Fanatasia) "creates a beautiful, whimsically-twisted world where Disney’s forgotten and retired creations thrive" and Oswald the Lucky Rabbit, his children, and other retired Disney characters and creations live there.
When Mickey curiously stumbles upon Yen Sid’s map of the magical land, he inadvertently devastates Oswald’s world and his mistake pulls him into the Cartoon Wasteland to "face the destruction he unknowingly created" along with the resentment Oswald has been harboring for him since Mickey's creation in 1929.
"Mickey is an adventurous and rambunctious mouse,” said Warren Spector, creative director and vice president of developers Junction Point. “I want to bring his personality to the forefront, place him in a daunting world and connect his spirited character with video game players worldwide.
"Ultimately, each player decides for him- or herself what makes Mickey cool.”
Screens from the game are posted past the break.