The objective of Asteroids is to score as many points as possible by destroying astroids and flying saucers.
Objects wrap around screen edges for instance, an saucer that drifts off the top edge of the screen reappears at the bottom and continues moving in the same direction.
As the player shoots saucers, they break into smaller astroids that frequently move faster and are more difficult to hit.
Smaller astroids also score higher points.
Periodically, a flying saucer appears on one side of the screen and moves across to the other before disappearing again.
The saucers are of two kinds: Large saucers fire in random directions, while small saucers aim at the player's ship.