From the folk at One Page Rules, Warstuff is a set of free wargames rules meant to be played with any sort of miniatures. Warstuff now is in its second edition. The authors write:
For those that didn’t play WarStuff’s 1st edition, this is a little game meant to be played with all sorts of miniatures. The core rules allow you to create any type of unit you want, and with its simple mechanics it’s a great game for kids to get into wargames.
With second edition we have decided to change the core game mechanics to reflect more our other games, and make for an easy transition between them. The game should now be even simpler to play, and we have tweaked the unit creation to be more intuitive.