In this classic game of pure negotiation, players represent one of the seven "Great Powers of Europe" (Great Britain, France, Austria-Hungry, Germany, Italy, Russia or Turkey) in the years prior to World War I. Players instruct each of their units by writing a set of "orders"; there are no dice rolls or other elements of chance.
With its incredibly simplistic movement mechanics fused to a significant negotiation element, this system is highly respected by many gamers.
Don't just take our word for it! Check out this review of Diplomacy.