If you don't have Wii Fit (or you just don't want to get so physical with the game) you can still use the Wii remote, as you try to manoeuvre your spherically-enclosed simian through the maze-like levels. Picking up bananas as you go is as complicated as the game gets, but you'll find it a cunning test of concentration and balance.
For the first time the single player levels have a new co-op mode, where a friend can help by blasting away obstacles from your path. Or if you want to get even more sociable there's the usual bizarre multiplayer mini-games, including a sky-diving game and a chance to play as a monkey fireman.