Nine Over Ten 9/10 has put up a review for Crap of Defense for the iPhone. The game has a unique place among the plethora of Tower Defense games on the mobile platform as it has the player manning a single cannon against hordes of troops.
The limited number of ammo will force players to choose their shots wisely by waiting for large groups and aiming just before them to take out large chunks.
Helping players are a bunch of power-ups that are obtained from blowing up troops. These include mines, speed-ups that decrease cannon re-load time, freeze bombs to slow down large groups of enemies and air strikes.