In the game, you only need to beat a certain amount of levels in a world to access a boss. So I was thinking maybe there could be Any% where you beat the required amount of levels, go to the boss, get the next world, rinse & repeat 3 times, an 100% where you beat all the Light World levels, 100% + Dark World where you beat light world + dark, and a True 100% where you collect all the collectables.