Caverns of Mars is a computer game for the Atari 8-bit computers, programmed by Greg Christensen and published by Atari Program Exchange (APX) in 1981. It became the best selling APX title of all time, eventually being released by Atari in game cartridge format.
The game is essentially a vertical-scrolling version of the arcade game Scramble, with the twist that the player must re-trace their steps through the map to finish the levels.