Caverns of Mars

Caverns of Mars is a vertically scrolling shooter for Atari 8-bit computers written by Greg Christensen, then a high school senior, with some features added by Richard Watts. It was published by the Atari Program Exchange in 1981. Caverns of Mars became the best selling Atari Program Exchange software of all-time and was moved into Atari, Inc.'s official product line, first on diskette in 1982, then on cartridge in 1983. In Caverns of Mars, the player descends into a cave and at the end must retrace their steps back to the top.