Cars!

Cars! is a set of free wargames rules for auto combat.

Urban Warzones Rules

Urban Warzone is a set of free wargames rules for near-future urban combat in a post-apocalypse world.

Wastelands Post Apocalyptic Wargames Rules

The author writes:

Wasteland is a game of post-apocalyptic warfare between small bands of desperate fighters. You can play it as a skirmish war game using the character archetypes and weapon lists but it’s also designed to allow you to play fast-moving and memorable campaigns with two or more players.

Fallout Wasteland Warfare Game

Mophidus is offering free PDF core rules for their Fallout Wasteland Warfare game, based on the Fallout video game series. They also are have a free Fallout: Wasteland Warfare Getting Acclimated pdf with some basic scenarios and a guide to help start play. Other free offerings are Fallout Wasteland Warfare Dice and Ruler Info and high res player cards.

Autokill Auto Combat Game

Autokill is a set of free wargames rules for vehicular combat.