Air War 1917 is a barebones — and free — version of Wessex Games’ AirWar: 1918 biplane combat rules.
world war One
Great War Spearhead Scenario Generation System
If you’re out of game ideas, here’s a scenario generator for Spearhead: Great War.
Making Trench Systems
Iron Hands has an illustrated article on making trench systems for your 25mm – 28mm miniature wargames. The principal ingredients are concrete patch, rocks and fiberboard.