I was on GameFAQS, and someone found what appears to be screenshots of 2 mini-games. One that shows Sonic, Knux, Amy, and what looks like the genie in a fiddle contest, and another that show the characters in front of balloons doing something.
Also, apparently this game has already been rated E, which seems like it got rated awfully fast compared to Shadow, Riders, Rivals, and StH.