User summary Invaders from Outer Space is a simple arcade style game pitting the player against encroaching aliens. The player uses a joystick to aim and fire "base" weapons against an invading fleet of saucers. The base can sustain three levels of incremental damage before the game ends. Player firepower decreases with increasing damage level. The program source code was written by David H. Markley and published in Compute!, Issue 11, April 1981.