Heart of Oak, Skin of Iron is a set of free wargame rules for naval combat in the years 1852 – 1870.
Ysgarth Fantasy Role Playing System
I remember Ysgarth from my role playing days in the late 1970s. The game first was published in 1979. It was one of a number of fantasy rpgs that I remember we tried before finally settling on the Warhammer Fantasy Role Play.
Ysgarth has got a pretty complex system of skills and attributes, but action is resolved on a simple d100 (that is, you roll 2d10s and read them as separate decimals)
Burning Rome: Barbarian Uprising
Burning Rome: Barbarian Uprising is a free print-and-play, standalone expansion for the commercial game, Burning Rome. It’s free because right now, it is in the prototype stage, so I suspect it won’t be up long.
Both Barbarian Uprising and the original Burning Rome are two player card games are two-player, deckbuilding, tactical card games.
Vehicular Pursuit Rules For Fistful of Kung Fu
The Osprey Rules A Fistful of Kung Fu 
OPUS – One Page Universal System
OPUS is a one page, universal role playing system.