It's interesting that the game is called Darwin and the 'unbeatable' program was one that took on evolutionary properties.

More at: http://www.cs.dartmouth.edu/~doug/darwin.pdf

(Probably should have submitted that as the primary link.)

Is there a more advanced (online) version? Something similar to RoboWar but w/o having to install Visual Basic?

Do you know Core Wars? It's doesn't count as the same game, but shoots into a similar vein.

see also corewars