tower defense

Tower Defense (TD) is a subgenre of strategy games in which the objective is to defend the player's territories or possessions by disrupting enemy attackers or stopping enemies from reaching an exit, usually achieved by placing defensive structures on or along their path of attack. This usually means building various structures to automatically block, disrupt, attack or destroy enemies. Tower defense is seen as a subgenre of real-time strategy video games, due to its real-time origins, although many modern tower defense games include aspects of turn-based strategy. The strategic choice and positioning of defensive elements is an essential strategy of the genre.