The universe is threatened by an invasion of trans-dimensional monsters. Reclaim the territory by cutting off parts of it. Lock the monsters in for extra points, but do not hit them or their portal, as this will take your life. Collect bonuses to acquire sort term extra powers when you hit the space bar: a B will boost your speed, an M will allow you to shoot and a S will release a small shockwave.
Use the arrow keys to move and the space bar to activate your bonus powers. Press the space bar to start the game.