Flotilla is a set of free wargames rules for star ship fleets of twenty to thirty ships.
science fiction
Dreadnought Arena Combat
Dreadnought Arena Combat is a set of free wargames rules for arena combats between war machines.
Xenocide Firefight
Xenocide Firefight is a set of free wargames rule for science fiction games. Troops are organized in squads.
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.
Frontline Skirmish Game For MegaBlox
“a versatile, yet simple turn-based strategy game that is fully customizable. The game is designed to make use of Mega Bloks Halo sets, but you can use any kind of equally-sized figurines including cheap army men, and is meant to be played on any kind of table or flat surface. Similar to games like WarHammer 40k or even chess, Frontline Skirmish contains very loose, simple rules and maximum customization.”
The game is on the pay-what-you-want model.