Diplomacy is this board game where everyone starts as a country with different footing and builds alliances and usually, by the end of the game, people choose break those alliances in spectacular turns of fate. In the one game I played in like 7 years ago, someone at the end of the game completely went back on all of her alliances by surprise to pull out an unshared victory and it was awesome.
Now if I can just find a copy of the game, 6 other players (no more no less), and 4 hours to play it in, I'll be set. This is why I'm best off not owning this game: it would just sit on the shelf and make me sad. Regardless, I have just added it to my "Want in Trade" list to see if someone will trade me a copy.
Edit: Trade sent and accepted.