One Page 40K Rules

One Page 40K Rules are a set of simple rules for the 40K Universe. The authors write:

One Page 40k is a single-page ruleset designed to be fast to learn and simple to play. It serves as a great introduction to the Warhammer 40.000 universe for people who are new to the game, and as a way to play quick games for veterans of the franchise.

Warhammer American Civil War Variant

The Cops.NU site has a Warhammer 40K variant for the American Civil War. I think it could work.

Warhammer Colonials!

These aren’t exactly free wargames rules, but if you already own a set of Warhammer 40K, this is worth checking out. Jervis Johnson has provided this page of colonial amendments to Warhammer 40K. These also would be a good way to introduce fantasy and science fiction wargamers to historical miniatures games.

Warhammer Colonials!

Imperial Guards Vs Zombies Rules

Imperial Guard vs Zombies is a set of modifications for Warhammer 40K

Zombies vs. Imperial Guard (Warhammer 40K Mod) Rules v1.5

GrimDark Racing One Page Rules

GrimDark Racing is a set of simple rules for races in the Warhammer 40K universe. Just use models you already have. There’s plenty of violence, of course.