Xenophobe

The NES port of Xenophobe, a 1987 arcade game. The goal of each level is to defeat all the aliens before time runs out. Levels may contain more than one floor, and players use elevators or holes to move between floors to defeat all of the aliens. Players can also pick up more powerful weapons and other items to help in their eradication of the aliens.

Starbases, moons, ships, and space cities are infested with aliens, and the players have to kill the aliens before each is completely overrun.