Two castles, separated by a mountain, try to defeat each other with their
cannonballs, either by killing the opponent's king or by weakening the
opponent enough so that the king capitulates.
Ballerburg was originally written 1987 by Eckhard Kruse, for the Atari ST
machines (which were brand new computers at that point in time). Over 25
years later, here's finally the adaption of the original source code to
modern operating systems.