Invasion from Outer Space

Invasion from Outer Space is a 1-player arcade game for the TRS-80.

The player controls a small vessel on the bottom of the screen that moves horizontally, and can fire vertically upwards. Streams of alien vessels move horizontally until they reach the side of the screen, at which point they move down one row and move back the other way. The player has 3 shields to help protect them from alien fire, and the player loses a base when hit. The player has a total of 5 bases, and when all are lost, it's game over. The alien swarm starts 1 row lower for each level completed.