From the magazine:
Play online at bbcmicro.co.uk:RAM Wars is a game in which two computer programs battle against each other for domination of the computer's memory -- the RAM.
It is open-ended because you create the battle programs yourself, and they can become more complex and intelligent -- only your skill is the limiting factor.
You write the battle programs in Redcode, which looks like assembly language, but only has eight instructions -- so it is quite easy to learn. They are compiled by the Redcode Compiler into M-code to be loaded into the Mars program (Memory Array Redcode Simulator).
The two battle programs are loaded in a memory array with 1024 elements within Mars. It then runs each routine, carrying out one instruction from each alternately.
Each battle program is trying to make the other crash, and the one that does this first is the winner. If after 2000 moves neither has succeeded in wiping out the other, the longer is declared the winner.