I was a diplomacy nut in college (I ran a 3 move a week game where we left the official board in my publically accessable living room). Its a great game when not played over the board. When played over the board:
a. you never finish
b. you can tell who is talking to who, so people do not break deals enough
c. because you never finish people make up rules like whomever has the most pieces at a certain point wins, and the defeats the point of the game.
The point of the game is to obtain over half the cities. Most of the strategy involves the various stalemate lines which are mulually re-inforcing positions that you can't break through. If one alliance has control over a stalemate line, they can only tie, they can't lose, unless the alliance falls apart...
If all the players remaining agree, a n-way tie is declared. Having 1 city is just as good as having 15 for purposes of an n-way tie...
I once played over the judge server (university of washington), which wasn't quite as fun. Although at that time it was easy to hack the international mail server and send e-mails to opponents supposidely from other opponents, and stir up trouble that way...