Atlantis

Atlantis is a 1-player arcade game for the Apple II.

Defend the underwater city of Atlantis from alien invasion. The player controls a vehicle called a Neutralizer on the bottom of the screen, which can move sideways and fire vertically. The aliens fire upon the city of Atlantis below, and if the shot reaches the bottom of the screen, it leaves a hole in the shield protecting Atlantis. If the Neutralizer is struck, it is destroyed. If the player loses 3 Neutralizers, or if the shield covering Atlantis is struck 3 times in the same location, then it's game over.