These one-eyed aliens were having fun together, when all of a sudden an evil professor came to assail their castle with his army of robots. Of course they won't let them overpower them, and they'll do their best to kill all the robots before these evil creatures reach the castle! You can play this game in the 'regular' or 'survival' mode, and within these modes you can choose the easy, normal or hard mode.
Use WASD to move around. Press the left mouse button to shoot. Use 1-6 to change weapon. Press the spacebar step into or out of a turret when you're standing close to it. Use P to pause the game.