Slow reply, but two things:
Whether that is game theoretically sound highly depends on the other player's behavior. If it makes other players afraid to stab you for fear of retribution in the next game, then yes, it works. But I think that among experienced diplomacy players, it is more likely to get you excluded from the game entirely. Also people will be less likely to ally with you in the first place if you have a reputation if responding badly to stabs.
This kind of behavior is explicitly against the rules in most online diplomacy communities. Because it ruins the fun of the game. Diplomacy as a game works best when everybody is really playing to win with a cut-throat, no holds barred, sell your own mother if needed, kind of style. A player who is meta-gaming is not playing to win for that individual game, so it lowers the experience for that individual game.
(Of course tarnishing someone's reputation, deserved or undeserved, based on actual or made up previous games, is an entirely valid strategy. So long as you play each individual game with the goal of maximizing your performance in that individual game, keeping previous games in mind is perfectly fine.)
Related: Diplomacy as a Game Theory Laboratory by Yvain.
I've been floating this idea around for a while, and there was enough interest to organize it.
Diplomacy is a board game of making and breaking alliances. It is a semi-iterative prisoner's dilemma with 7 prisoners. The rules are very simple, there is no luck factor and any tactical tricks can be learned quickly. You play as one of the great powers in pre-WW1 Europe, and your goal is to dominate over half of the board. To do this, you must negotiate alliances with the other players, and then stab them at the most opportune moment. But beware, if you are too stabby, no one will trust you. And if you are too trusting, you will get stabbed yourself.
If you have never played the game, don't worry. It is really quick to pick up. I explain the rules in detail here.
The game will (most likely) be played at webdiplomacy.net. You need an account, which requires a valid email. To play the game, you will need to spend at least 10 minutes every phase (3 days) to enter your orders. In the meantime, you will be negotiating with other players. That takes as much as you want it to, but I recommend setting away at least 30 minutes per day (in 5-minute quantums). A game usually lasts about 10 in-game years, which comes down to 30-something phases (60-90 days). A phase can progress early if everyone agrees. Likewise, the game can be paused indefinitely if everyone agrees (e.g. if a player will not have Internet access).
Joining a game is Serious Business, as missing a deadline can spoil it for the other 6 players. Please apply iff:
If you still wish to play, please sign up in the comments. Please specify the earliest time it would suit you for the game to start. If we somehow get more than 7 players, we'll discuss our options (play a variant with more players, multiple games, etc).
See also: First game of LW Diplomacy
Well, the interest is there, so I've set up two games.
Game 1: http://webdiplomacy.net/board.php?gameID=164863 (started!)
Game 2: http://webdiplomacy.net/board.php?gameID=164912 (started! First phase will be extended to end on the 4th of August)
Password: clippy
Please note a couple important rules of the webdiplomacy.net website: