A warped and twisted war game. It is considered to be the ultimate board game by some (warped and twisted) people. The object of the game is to take over Europe. But it is not Yet Another War Game. The combat rules are simple, abstract, and involve no dice, cards, or any random element. Instead of moving one player at a time, all players write down their moves in secret, and then all moves are revealed and take effect at once. Negotiation, the formation of alliances, and the betrayal of these alliances are what make the game interesting, rather than war simulation and historical reenactment.
The 4th edition rulebook is available online from Avalon-Hill (now a division of Hasbro) here. The Diplomatic Pouch has many good resources.