Afterglow Skirmish Warfare In The Far Future is a set of free wargames rules for 28mm figures and is designed to be used with a variety of manufacturers.
rules
Strongbow Feudal Warfare Rules
Strongbow is the Perfect Captain’s set of free wargames rules for feudal warfare from 1050-1300AD
Clauswitz’ War: Theatre-Level Napoleonic Campaign Rules
Clauswitz’ War: Theatre-Level Napoleonic Campaign Rules is a set of free wargames rules for Napoleonic campaigns. The author writes:
These rules are designed to be used to represent theatre-level campaigning with armies of several corps per side during the Napoleonic period. Each turn is a day, and maps covering an area from 100 – 500 miles on a side with good detail (roads, rivers, towns) should be used. The intent of these rules is not to depict campaigning 100% accurately, but to provide a referee with basic guidelines for running a Kriegspiel-type game for the generation of tabletop engagements. All dice are ordinary 6-sided dice.
Battlefleet 1900 Pre-Dreadnought Naval Warfare: 1890-1905
The War Times Journal has a set of free Pre-Dreadnought Naval Warfare rules, designed for 1/3000 scale miniatures.
Panzer War rules
In 1979, Steve Lorenz published Panzer War, a set of miniature wargaming rules for World War II microarmor. It was moderately successful, and in 1981, the second edition, Panzer War II was published. Having long since sold out, Steve has elected to offer these successful wargames rules free as a download.
Steve describes his set:
Panzer War is a set of war game rules simulating World War II armor warfare that will eventually use a variety of scaled miniatures. Currently it is scaled for 1/285 scaled models. Each player can assume the command of a platoon or company of troops. Panzer War includes rules covering weapons, vehicles and troops used during the conflict from 1938 through 1945. Warfare on and over the battlefield is simulated in a detailed and realistic manner. The scale being one vehicle model for one real vehicle and one infantry stand per infantry squad. The game may seem complicated at first once the basic rules are understood and experience is gained they will become second nature to the players. After familiarizing themselves with the basic rules players should move on to more advanced rules one step at a time.
And yes, there are a lot of charts and tables.