Use your mouse to interact with the game. The aim of the game is to decide which towers to build and what kind of upgrades to use in order to create the perfect defense against hordes of cyberoids coming up. Towers are seperated into three categories based on which targets they can destroy: ground, air and phantom units. Some towers can provide defense against more than one unit type. The main trick of base defense is tower upgrades. There are three kinds of tower upgrades available in the game: range, damage and reload. The energy meter represents the total amount of energy available for the player which can be used to assemble new towers and unlock upgrades. The status meter shows information on base integrity. When it goes to 0, the base has been destroyed and the game ends.