Warlord Games offers its Dr. Who Exterminate rules free for the downloading.
Rules: Science Fiction
First Law Override: Science Fiction Skirmish Rules
First Law Override is a set of free wargames rules in beta edition for science fiction skirmishes. The author writes:
First Law: Override
A game of futuristic combat, espionage, and cyber warfare
Set on the world of Honos, a terraformed planet on the far fringe of the Milky Way Galaxy, First Law: Override is a sci- campaign skirmish game where humans and aliens battle it out using combat, espionage and cyber-warfare. Using a 28mm Open Source model system, build your force of elite soldiers, assassins, hackers and freedom fighters before taking to the conflicted streets of Honos, where both fortune and death awaits at every corner. This book contains all of the rules needed to play a game of First Law: Override
Fallout Wasteland Warfare – Creatures of the Fog Free Factions
Modiphius offers a free packet of factions for their Fallout Wasteland Warfare game.
A Sky Full of Ships Space Fleet Rules
A Sky Full of Ships are a set of free wargames rules for space fleet rules in which the player plays an admiral, commanding large fleets:
Instead of being just the captain of a few ships, you take the place of an admiral, commanding entire fleets. Using simple, fast moving game mechanics, these rules attempt to portray the important aspects of huge fleet engagements without becoming too bogged down in time consuming detail. They’re for those players willing to sacrifice some complexity to achieve a fast moving, playable, and most importantly, FUN game.
Laplace, Newton & Lagrange Space Combat Game
Laplace, Newton & Lagrange is a is a
game of ship to ship combat in outer space. Using a unique movement system that forces players to deal with momentum, and a fast and simple combat system.