Ramshackle Games offers Nuclear Renaissance, a set of free, downloadable rules for playing skirmishes set in a post nuclear holocaust. There’s both a full color, and a printer friendly set.
The game puts me in mind of one of the favorites from my childhood — Gamma World. You had to love that chart for checking out various objects you discovered.
New Vegas is a set of free wargames rules designed with playing a Fallout style post apocalypse game in mind.
Wasteland Racing is a set of free wargames rules for deadly races in a post apocalyptic world.
Marcus Reynolds offers Warriors of the Wasteland, a set of skirmish level science fiction rules that he devised when he became tired of the shenanigans of a certain miniatures gaming company who shall remain nameless but whose initials are GW.
Fallout is a legendary computer role playing game. Set in a post nuclear world, it has a 1950s science fiction aura. Here’s a miniatures game set in that world.