Defeat countless enemy waves trying to make their way into your territory. As the game progresses build more and more turrets, upgrade them, and wreak havoc upon those that try to cross you. Beware! The enemies get tougher and tougher every round. You should also mind that some parts of the land are unfit to rise structures and as enemies get more and more clever, forcing you to defend parts of land with diminishing opportunities to rise your defences...