The Lights Are Going Out is a set of free wargames rules for WWI in 1914. The rules are designed for 15mm figures.
“When Technology Meets Tradition” is a set of rules for wargaming early modern warfare conflicts, roughly from 1895-1915. The emphasis of the author is on early World War I (1914-1915) but other period wars are also of interest, such as the Russo-Japanese War or the Boer wars. The rules are fast-play and focus on the problems faced by military tacticians during early modern warfare: when outdated linear tactics and love of the offensive ran head-on into lethal, accurate, and rapid firing weaponry.
Here’s a free ebook from Amazon that may interest some. Summary:
Francis Pegahmagabow has long been considered the most prolific killing machine of the First World War as he has been credited with over 378 deaths. This book chronicles his reputation as both a sniper and scout as the Canadian/British Army allowed him to roam freely throughout the “No Man’s Land” region of France where he singlehandedly took down German troops. We also look at his later life as he suffered from “shell shock” (now known as post-traumatic stress disorder) and was deemed a “mental case” by the local Indian agents who oversaw his tribal band.
Over The Top is a set of free wargames rules for brigade level games set in the First World War.
Wartime Journal offers 1916, a set of free wargames rules for battalion and regimental combat in World War I.