Tired of Warhammer 40K? Try Slammer a set of free wargames rules by Chris and Alex Nicole. The rules set is not tied to any particular set of science fiction miniatures, and there are army lists for a wide variety of troops — even Zulus! ??? (For those hordes of primitives versus superior technology games).
skirmish
Blasted Planets Skirmish Rules
Blasted Planets is a set of free wargames rules for science fiction skirmishes.
Blasted Planets Skirmish, is basically a set of house rules a few friends and I use to play games with my Sci-Fi figures. I am not trying to model a “Hard” Sci-Fi environment here. I’m borrowing as much from Horror and Fantasy as I am from Sci-Fi. I mean how serious can you be. When you have, Dog headed, Gator men chasing an Elephant guy around an Omni Field generating White rabbit? There is enough “real” world framework here that basic tactics work (most of the time). But enough of a fantastical element that you really can’t count on the idea that the Fin headed alien with the pin gun is going to nail the cave man with the rock every time.
Brains: The Hunger
Pictors Studio offers a quick little Zombie game called Brains: The Hunger They also promise updates featuring soldiers, martians and “other neat stuff”
La Petite Guerre Skirmish Rules
La Petit Guerre is a set of free wargames rules for small scale actions in North America in the 17th – 19th century.
Zombie Skirmish Rules
Table Top Titans have released Twilight, a set of free miniature wargaming rules for skirmishes in a zombie plagued world.