Phobos is an RPG of the “Wonders and Terrors of Technology and Magic.” There doesn’t appear to be any real background, but the system is geared toward a modern setting with magic. It uses an open-ended d20 system (in which you roll again if you score a 20).
Vaporoare is a role playing game, but as is the case with such, it’s full of ideas for skirmish type miniatures games. The author writes:
Vaporoare is a role-playing game of weird science and mad magi in Victorian-era Europe. It imagines a world where Jules Verne wrote technical manuals for ether machines instead of fiction; Mary Shelley penned the autobiography of Dr. Frankenstein, and H. P. Lovecraft didn’t know what he was getting into. It is the world described by Edgar Allan Poe, Lord Dunsany and J. R. R. Tolkien. Europe is alive with races of fiction: elves dwarves and gnomes. These people have lived together since the beginning of time, and now they face their greatest challenge: the Industrial Revolution. Magick is dying, and technology is on the rampage.
Steve Jackson’s GURPS (Generic Universal Role Playing System) is one of the grand old men of the role playing world. The game provides one of the most realistic, detailed gaming systems ever. Because the combat system is so good, I know of many miniature gamers who use it for skirmish games. Steve Jackson games has released a free “lite” version of the rules as a pdf download.
Dead Simple Steampunk is a set of one-page RPG rules for settings in a Victorian science fiction setting. There’s also a one-page setting and one page for equipment.
Living Dead is a set of free roleplaying rules for the zombie apocalypse.