The Portable Wargame: Ancients is a set of free wargames rules for ancients wargames using a gridded surface and individually based figures. The Ancients version is one of several using the same system in different periods.
Miniatures Rules
Flip It Paper Combat
From the authors:
Flipit: Paper Combat is a fast-paced tabletop miniatures game in a setting similar to WWII. Players lead forces from one of the four major nations into the conflict for Jurop. Armies are built of models players can download, print and build for almost free (you still have to supply the ink, paper, and glue). There are simple starter rules available, which may be supplimented by optional advanced rules to make gameplay more challenging
Hat Tip to Martyn for the link.
Morschauser’s Frontier Wargames Rules
Joseph Morschauser’s wargames are designed to be played on a square grid. The Frontier Wargames set is for colonial games.