If you are lucky enough to have acquired HeroScape terrain, you may be interested in these Colonial Rules For Heroscape terrain.
rules
Heroic Samurai
Jim Wallman offers Heroic Samurai, a set of free wargames rules for clan warfare in feudal Japan.
Leave No Man Behind Somalia 1993 Rules
Leave No Man Behind is a set of free wargames rules for gaming the 1993 Somalia conflict. They are designed as fast-play, with up to 150 figures, including vehicles and helicopters.
Table Top Quidditch
Table Top Quidditch is a set of free wargames rules for playing the favorite sport of wizards.
Poly Wars Dice Combat Game
Poly Wars is a set of free wargames rules in which the dice themselves are the miniatures.