[Enigma]

A really good one is the The Operational Art of War: Century of Warfare Edition.

There are dozens of scenarios and it gives the best of the old board wargame feel. I am currently playing a WWI scenario with a map covering all of Europe plus the colonies. I fully expect to be playing this game out for the next 3 years. (we are averaging about 1 turn a week - each turn takes roughly 6 hours)

I have Emperor of the Fading Suns but I do not think it works anymore with Windows XP. How do you make this game work. I do not remember if it is multi-player. It is a game that would be a great multiplayer I think.