Press the space bar to shoot and destroy asteroids. Use the left and right arrows keys to rotate the ship and the "top" arrow to move forward.
The object of the game is to shoot and wreck space rocks and saucers while not crashing into either or being hit by the saucers' counter-fire. The game gets more enthusiastically as the number of space rocks increments.
You need to control a triangular ship that can rotate left and right, fire shots straight forward, and thrust forward. When the ship starts moving toward a path, it will proceed toward that path for a period without player intercession except if the player applies push in an alternate heading. The ship inevitably grinds to a halt when not pushing.