Boonta Eve Classic is a set of free wargmes rules for pod racing in the Star Wars Universe. The rules are designed for use with those old Galoob Micromachines, which can still be had for a reasonable price on Ebay:
Miniatures Rules
American War of Independence Wargames Rules
American War of Independence is a set of free wargames rules based on Neil Thomas’ Napoleonic Wargaming and Ancient and Medieval Wargaming. Interestingly, all movement is based on “base widths.”
Soldiers In Time Rules
Soldiers In Time is a set of free wargames rules that let you conduct skirmishes between soldiers of different eras.
I want to play the guys with the machine guns against the stone throwers.
Away Team Astro Miniatures Skirmish Game
Away Team is a set of free wargames rules for a Star Trek-style landing party expeditions.
There’s also a set of 15mm not-Star Trek miniatures.
Firefight Mass Combat
Firefight Mass Combat is a set of free wargames rules originally written for use with Alternative Armies’ 15mm science fiction ranges.