2.3 Entrance into the Mainstream Market.They can also be single-player, cooperative, or multiplayer - varying from title to title. TD Games can be simple or complex, turn-based or real-time and all involve a degree strategy. TD Games are usually very easy to pick up however hard to master. Winning is usually defined as surviving the onslaught of creeps (The human's towers eliminate all (or a sizable portion) of the creeps) and losing is defined as the creeps reaching the end of the map before your towers have a chance to take them out. Each eliminated creep results in gained resources, these resources are then stockpiled by the human player to buy more towers, or upgrade current ones. These towers have the ability to shoot, damage, halt, and eliminate creeps from the map. In order to succeed in the TD Game genre, human players have to allocate resources in order to build defensive towers. The TD Game genre is generally comprised of a human player who allocates resources to build 'Towers' in order to prevent enemies (commonly referred to as 'creeps') from passing through the human players map.
Tower Defense Games or TD Games are essentially a sub-genre of strategy games. A screenshot from Defense Grid: The Awakening (2008)
