Ed Teixeira of Two Hour Wargames has released the third edition of his Chain Reaction (and Swordplay!) miniatures wargame as a free download. If you're not familiar with this game, it's an excellent set of fast-play skirmish rules that can be played with any figures.
Models are divided into Stars and Grunts. The Stars are sort of like PCs with various advantages (Cheating Death, Free Will, etc.) and attributes (Born Leader, Nerves of steel, etc.) Grunts are, well, grunts. All models have a single stat, Reputation, or Rep, ranging from 1-6. The player rolls two dice (on most occasions) trying to roll Rep or less (this is a roll low game). The dice are read individually, not added. This gives three possible results: Pass 2, Pass 1, and Pass 0.
In place of the standard moral system the game uses a unique Reaction system. That means models that come under attack must make a Reaction Test that may result in an Involuntary Action. (Now you see why the Free Will advantage is important.) This gives the game a very dynamic, unpredictable feel. The Reaction System is also something most players either love or hate. As Ed himself says, "It’s not for everyone. If you like total control of your forces then just keep walking because you’ll hate it."
The Reaction System is best suited to what I think is the finest of the published versions of the game, All Things Zombie. It really brings the shambling undead to life, so to speak. The game's add copy gives a good overview.
"ATZ takes you to where no other zombie game has before. Yes, it starts on the first day of the outbreak, but then let’s you continue your life building your very own future. It’s a game where every detail has been covered, as you first escape the soulless creatures that threaten you, then hunt them down and take back what’s yours.
On the way there you’ll find out that maybe your most dangerous enemies aren’t the zombies, but maybe your neighbors or sometimes your friends. ATZ can be played solo, cooperatively with everyone on the same side, or competitively with everyone against one another. ATZ can be played as a one up game or part of an ongoing campaign."
If the undead aren't your thing, Simon Norrington has rules on his website for using CR to run Star Trek TOS and Dr. Who games. They're written for the second edition, but should work fine with the new third edition.
So give Chain Reaction and Swordplay! a try. Ed says, "And if you don’t like CR 3.0 it’s all good. Because really it’s all about playing games that you like."