Star Sentry

Star Sentry is a 1-player space themed arcade game for the Atari 400/800.

Suddenly the small ice planet planet Thule is surrounded by alien life orbs determined to change the hostile environment to suit their own needs. Unfortunately, you are stationed in a small outpost build atop an icy peak, and will certainly be destroyed as the ice melts. You must destroy the aliens before they melt your frozen home.

A 1 player horizontal scrolling shooter, the player controls a small spaceship which can move in all 4 cardinal directions. The ship has a small cannon, which can only fire horizontally forwards. From the right stream alien space orbs, and at the bottom of the screen constantly changing rocky ground poses a navigational hazard to the player. The player's goal is to maximize score by shooting alien orbs, which take 3 hits to be destroyed. There are a total of 9 difficulty levels. The player has 3 ships, and when all are lost, it's game over.