You and your partner Erin are engaged to eliminate aliens in another solar system. You scent money so you decide to accept the mission. You can play this game in the 'main campaign' and survival mode. In the 'main campaign' mode you have to accomplish all kinds of missions. In survival mode you try to stay alive as long as possible by repelling enemy attacks. Eliminate as many creeps as possible and don't let them get you!
Use WASD to move and the mouse to aim and to shoot.