Dungeon Delvers is a set of free dungeon crawl rules.
rules
Renaissance Naval Rules
David Heading offers a set of free wargames rules for Renaissance Naval Battles.
On To Waterloo Napoleonic Rules
On To Waterloo are a set of free wargames rules based on the On To Richmond American Civil War rule set.
Argad Medieval Skirmish Rules
Argad is a set of free wargames rules for skirmishes in the dark ages and for pirates in the 17th and 18th centuries.
Victory Without Squares
Victory without Squares is a modification of the Victory without Quarter English Civil War Rules System. Both are free wargames rules, with the “without squares” version using inches, rather than squares for movement and range.