Between 1968 and 1970, wargaming pioneer Charles Grant wrote a serialized wargames guide in Meccano Magazine. The serial is now available as a free download. This serial eventually became his classic Battle: Practical Wargaming.
Rules: General
Road Cycling Tour Miniatures Game
Fog’s Soldiers offers a set of free miniatures rules for Road Cycling, and not incidentally, a line of miniatures to go with it. You don’t need them, though, because you also can download printable rider tokens.
Brickhammer Lego Wargames Rules
Brickhammer is a set of free wargames rules for playing wargames using Lego and minifigs.
Minifigz Lego Combat Rules
Minifigz is a set of rules for combat with Lego figurines.
Plastic Brigade
Plastic Brigade is a set of fun rules for dollar store toy soldiers.