Escaramouche is a set of free wargames rules for skirmishes in the Pike and Shot era. It’s designed to be played with perhaps six figures per side.
Miniatures Rules
Reconstructed Sweet Home Rules For Ancient Battles
Blunders on the Danube Blog has a set of free wargames rules for ancients battles based on Charles Sweet’s classic set.
No Dachi Samurai Skirmish Rules
No Dachi is a set of free wargames rules for Samurai skirmishes.
Medieval Skirmish Rules
Richard Bradley’s Medieval Skirmish rules are offered for free on the Tyneside Wargames Club site. There actually are quite a few free wargames rules there. All look quite playable and fun.
Seven Years War Rules
Richard Bradley of the Tyneside Wargames Club offers a set of free wargames rules for the Seven Years War. The rules are designed for 15mm figures, where a battalion is represented by 3-4 bases.