World War One has not been covered as extensively as WW2, but nevertheless there are some excellent and awarded titles you should have in your library:
Strategic Level
- Paths of Glory – GMT Games (Rules – Vassal – Review – Strategy)
- Wings of War – Fantasy Flight Games (Rules – Vassal – Review – Strategy)
- World War 1 – SPI (Rules – Vassal – Review – Strategy)
- Guns of August – Avalon Hill (Rules – Vassal – Review – Strategy)
- Red Poppies – Worthington Games (Rules – Vassal – Review – Strategy)
- In the Trenches series – Grenier Games (Rules – Vassal – Review – Strategy)
Opening engagements – Through Mud and Blood – The Lost Generation - The pursuit of Von Spee – Grenier Games (Rules – Vassal)
Operations
- Strafexpedition – Europa Simulazioni – About the Italian Campaign (1915-18)