Defend the 10 planets from the invading vectors with your base gun.
Use the mouse to aim, click and hold the mouse button to build power, then release to fire. Unlock planets as you successfully defend each one.
Red blockers on later levels cannot be destroyed
Destroy passing satelites that fly across the screen, then shoot the power up they leave behind to gain new weapons for a short period of time.
Rebound your bullets of multiple enemies for greater scores.