Lou Coatney’s France 1914 is a free print-and-play, hex-and-counter boardgame of the German attack on France in 1914.
World War I
The Lights Are Going out WWI Rules
The Lights Are Going Out is a set of free wargames rules for WWI in 1914. The rules are designed for 15mm figures.
1916 World War I Rules
Wartime Journal offers 1916, a set of free wargames rules for battalion and regimental combat in World War I.
First World War History Website
First World War dot Com is a good resource for doing research into the war to end all wars.
Trench Assault
Jim Wallman presents Trench Assault, a battalion level game simulating a rush across no man’s land in 1916. Jim writes that it can be used with any scale figures, but that 1/300 or 6mm would be best because they are closest to the groudn scale.