Non-Stop Tower Defense In The Depths of Space. Your only goal is to stay alive. Choose your field of battle. You will have only seconds to deduce the enemies route as they advance toward your Mothership. Quickly build your defense turrets by tapping an empty block. Don’t build them too close together or they will destroy each other when they grow. Your defense turrets gain power and grow by killing the enemy. They lose power and shrink when an enemy invades your Mothership. If a turret shrinks too much, it will implode. When that happens, you must immediately rebuild, maybe this time in a better location. You get one point for each enemy your kill and you lose one point for each enemy that invades your Mothership. You have until Level 3 to get your act together. After that, if your score falls to zero, you have surrendered your Mothership. Otherwise, the game will continue for as long as you can stave off the enemy horde.