Medieval
Adapted from Comitatus to re-create the battles of the 14th-15th centuries in Western Europe.
This Weak Piping Time of Peace
Simple rules for a Wars of the Roses Game with 54mm toy soldiers.
North America
La Petite Guerre
Skirmish rules for the conflicts in North America. Free Download.
Ancients
Wargames rules for the end of the Roman Empire and the Dark Ages - AD 200 to AD 1100
An adaptation of the Comitatus mechanisms for Ancient wargames in the Classical Era (4th C BC to 3rd C AD)
Shieldwall
Recreate the atmosphere of Dark Age battles in the British Isles and Northern Europe.
Fast play rules for big battles in the Ancient world with 6mm figures. All are free downloads
Pike to Shot
Close Fire and European Order.
European Warfare in the age of Marlborough (1700-1720).
Close Fire and European Order XVII
An adaptation of CFEO for European Warfare in the 17th Century
Malbrook s'en va-t-en Guerre
Designed to re-fight big battles of the War of Spanish Succession with 15mm or smaller miniatures — a derivation of CFEO for larger engagements with a smaller ground scale.
Rules for Ancient Greek Hoplite battles. Published by the Society of Ancients the rules are available here.
Click on Blue Underlined Title to go to the page for the specific rule set.
QRS for skirmishes on the Canadian Northwest Frontier 1885. Free Download.
Simplified QRS for skirmishes of the French and Indian War (1754-1763). Free Download.
Loose Files and American Scramble
Andy Callan's excellent AWI rules as published in Wargames Illustrated Issue #1. I have adapted many of the mechanisms into my various rule sets.