Vortex

An explosion of black light has created a deadly Vortex. Your starbase has been entrapped in the middle of its gravitational pull, and alien kamikaze vessels are attacking you from 4 directions. You must fend off this alien assault for as long as possible.

Your starbase can fire in 4 cardinal directions, but remains stationary in the center of the screen. Long thin alien vessels come out of the 4 sides of the screen, and spiral towards the starbase. They must be shot before they contact the station, or the base is destroyed. The player starts with 7 starbases, but a new base is gained every 1000 points. Players can choose between 5 difficulty levels, and alien vessels move faster as the game progresses. The player gains points based upon the length of the alien ship, with shorter ships being worth more points. Gameplay is divided into phases, with an alien saucer attacking at the end of each phase.

The game ends when all starbases are destroyed.