It is a way of handling exceptions without having to propagate flags up through multiple levels of nesting.
The majority of tiered cakes are supported and constructed with dowel rods, which hold the multiple levels in place and keep the cake from imploding.
For a look that mimics that of a standard wedding cake, a decorator can set up a tiered cupcake wedding cake using multiple levels.
It doesn't offer multiple levels of difficulty, so once you beat the game, that's it.