All Quiet On The Martian Front is a great game set in an alternate history where HG Wells’ Martians return in 1908. It’s got a WWI vibe, with steam tanks and big cannons and motorcycles. You can take a look at the free rules here.
Victrix Miniatures has released a set of free wargaming rules called March of Eagles, which is designed to go with their plastic boxed miniatures. They write:
We commissioned Barry Hilton, League of Augsburg, to write a set of fast play Napoleonic rules. The rules are quick to learn, very realistic, extremely bloody and a game can easily be played within an evening. At present we are only publishing rules for infantry combat but we will be releasing supplements to cover artillery and cavalry.
These March of Eagles rules are included in each box of Victrix figures along with lots of cut out counters that are an aid to the rules. We have also included a very useful set of measuring devices within the sprue frame.
Zombie Escape is a Warhammer 40K modification for Imperial Guard versus Zombies
PZ8 WWII is a set of free wargames rules for fighting battles of the Second World War using 6mm (microarmor) wargames miniatures. They’re at the 6mm Yahoo Group.
PZ8 Sci Fi is a set of free wargames rules for using 6mm (microarmor) figures in a science fiction setting. They’re available on the Yahoo 6mm Wargames Group.