Defend against swarms of enemies units and watch them explode into pieces in each fast-pace level.
Earn money for upgrades to improve turret, fire rate, accuracy, ammo, health and speed. About the Swarms: They will accelerate towers you at all times, sometimes they orbit you, sometimes they attack you directly. Swarms become faster, stronger and more unpredictable. Swarms are fastest when they are large, as you destroy their members, they become less agile.