Beamrider

In Beamrider, you control a spaceship riding along one of five beams at the bottom of the screen. Your mission is to clear 99 sectors of hostile aliens.

Each sector requires you to destroy fifteen white flying saucers. Once they are gone, a sector sentinel appears and can be destroyed for extra points. Lasers provide your standard fire, while the more powerful torpedoes can destroy more enemies but are limited to three per level.

Additional enemy types appear on even-numbered sectors through sector 16. These enemies hinder your progress, but only the flying saucers must be destroyed to advance. A rejeuvinator can occasionally appear and grant an extra life if collected; shooting it instead transforms it into an enemy.