Kensi is a set of free wargames rules for samurai warfare ranging from skirmishes to large battles. The rules include a fantasy element, and the world is a not-quite-historical Japan.
fantasy
Wrath of the Gods Fantasy Skirmish Game
Wrath of the Gods is a set of free wargames rules for skirmishes with a classical mythological flavor.
Realm Fantasy Warfare Rules
Realm is a set of free wargames rules for large scale fantasy battles.
Chivalry and Sorcery 4th Edition – Free
The fourth edition of the venerable Chivalry and Sorcery RPG is available for free at RPG Now.
Free D&D Elemental Evil Players Guide
Wizards of the Coast offers the Dungeons and Dragons Elemental Evil Players guide as a free download.