Mobius is a set of free wargames rules for game set in the universe of Archie Comics’ Sonic The Hedgehog series.
Update: Mobius now is in its second edition.
rules
White Steeds and Seax
White Steeds and Seax is a variant of the Dark Age Infantry Slog rules, which include rules for cavalry.
Twilight Small Scale Skirmish Rules
Hasslefree Miniatures has a trial set of their Twilight Small Scale Skirmish miniatures rules.
NapNuts Western Gunfight Rules
The Napnuts’ Chew Boon Longe has a set of free wargames rules for western gunfights.
Unbreakable Future Ground Combat Miniatures Rules
Unbreakable is a set of free wargames rules for
a game of futuristic ground combat for 2 players. Each player assembles a platoon of crawlers, walkers, and powered armor squads and equips them with nukes, stasis rays, lasers, and more. Then the platoons meet in combat where they unleash terrible powers of overwhelming destruction. Fortunately, no one gets hurt. Thanks to amazing leaps in materials technology, the battlefield of the future will no longer be a dangerous place (for the combatants).