Naginata is a set of free wargames rules for samurai skirmishes.
WWI and WWII Naval Rules
Steve Burt offers a set of free wargames rules for WWI and WWII Naval combat.
The Last Human RPG
In this unusual free role playing game, you play a simple robot charged with defending the last human being. The Last Human is written by Nathan Russel as a part of the 24 Hour RPG Challenge.
Pencils and Powers Print-And-Play Game
Pencils and Powers is a print-and-play game that is billed as a “roll and write.” Basically, they’re on-page dungeons that are resolved through decisions and dice rolls. The link takes you to the inventor’s Facebook page. Click on the Play Game link to get to the files.
1943 World War II Rules
From War Times Journal, 1943 is a set of free wargames rules for battalion level combat in World War II.