The War Times Journal has a set of free Pre-Dreadnought Naval Warfare rules, designed for 1/3000 scale miniatures.
rules
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.
MEST – Adventures in Matter, Energy, Space and Time
MEST – Adventures In Matter, Energy, Space and Time is a set of free wargames rules for cinematic skirmish games. The authors write:
Matter. Energy. Space. Time. The MEST Narrative miniatures rules system is designed to be a flexible light-weight set of features that can work with numerous genres such as Swords & Sandals, Medieval, Swashbuckler, Wild West, Horror, Victorian Adventure, Pulp Heroes, Modern Battles, Future War, Sci-Fi, or Superheroes.
With these rules two or more players can simulate the last exciting minutes of derring-do, harrowing deeds, and heart-stopping acts of courage of any small-scale engagement pulled from any number of genres; from penny novels, serials, and otherwise. Will the dastardly villains win? Will the heroes prevail? Who lives? Who dies? The answers to these questions and more await your decision!
Necropolis Horror Skirmish Game
Necropolis is described as a:
Necropolis is a home-grown horror skirmish miniatures game that pits a small group of desperate heroes against a variety of horror enemies from zombies to vampires, werewolves, serial killers and anything else a fevered mind can come up with
Taking The Bull By The Horns
Taking The Bull By The Horns is a set of free wargames rules for Zulu War skirmishes in 1/300 scale.