Mike Mike Projectile Wargaming is a set of free wargames rules for games of that sort where you use some short of shooter (such as a rubber band gun) to knock over the figures.
Use with plastic only.
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.
Beer and Pretzels Modern Micro Armor
GHQ has a free pdf of its Beer and Pretzels Modern Micro Armor game, formerly a commercial effort, now a set of free wargames rules.
Beer and Pretzels WWII Micro Armor
GHQ has a pdf of its Beer and Pretzels WWII Micro Armor, originally a commerial set, now a set of free wargames rules.