Tree of Battles is a set of free wargames rules for battles of the 14th to 15th Centuries.
Rules: Pike and Shot
Border Reivers Rules
Border Reivers were raiders along the Anglo/Scottish border from the 1200s to the 1700s. Here’s a set of free wargames rules for playing out these skirmishes.
Koku Samurai Warfare Rules
Koku is a set of basic Samurai warfare rules with a mechanism for purchasing your troops.
Freebooter’s Fate Free Quickstart Rules
The publishers of Freebooter’s Fate, a commercial set of fantasy pirate rules has released a free set of quickstart rules.
A Splendid Victory ECW Rules
A Splendid Victory is a set of free wargames rules for the English Civil War. They’re designed for 28mm figures, but the basing system is flexible.