The Prisoner's Dilemma Drinking Game

The Prisoner's Dilemma Party Game

Derived from a post here.

This is based on the well-known game theory exercise known as The Prisoner's Dilemma. Briefly, it works like this: two players are arrested and interrogated separately, and each has two options: keep quiet, or sing like a bird in hopes of getting a deal -- without having any way of knowing what the other is doing. The results depend on their choices:

• If each keeps quiet, they are set free for lack of evidence (or convicted of a lesser offense).
• If one snitches and the other keeps quiet, the snitch is granted immunity and the other goes up the river for a long time.
• If both snitch, the book is thrown at each

The drinking game aspect is simple -- rather than time in prison, the penalty is taking drinks. The most obvious way to do this is to have the "loser" take the drinks him/herself; but for reasons explained below, it may be preferable to allow the "winner" to distribute the drinks among other players (e.g. even those that were not part of the "interrogation").

Rules

These rules assume that you're using a standard 52-card deck, though using cards specific to the game could provide greater flexibility.

1. Sort the deck by suit, and create three piles:
   • The Diamonds and Spades will be the Pairing Deck; shuffle it.
   • The Clubs will be the Penalty Deck; shuffle it.
   • The Hearts will be the Decision Deck; leave it sorted.
2. Deal one card from the Pairing Deck to each player (if there are more than 26 players, use another deck). Players should keep their card secret.
3. Those who were dealt the Aces step forward; one card from the Penalty Deck is dealt to each of them face-down, and a third is dealt face-down in the middle. The players may inspect their own penalty card, but may not tell the other player what their card is. The card in the middle remains hidden.
4. These players are each given two cards from the Decision Deck -- one representing 'Keep Quiet' and the other representing 'Snitch' (one way to do this is even/odd; another is to use face cards -- say, the Jack is the Snitch and the Queen is silent, though the advantage to using multiple cards is it becomes harder to recognize 'marked' cards)
5. Each player places the card corresponding to his/her decision and places it face-down on the table.
6. After both players have played a decision card, they are flipped over, and all of the penalty cards are revealed.
7. "Scoring" takes place as follows:

   	Player A Snitches	Player A Keeps Quiet
   Player B Snitches	Double Loss	Single Loss - Player A
   Player B Keeps Quiet	Single Loss - Player B	No loss

   • On a Double Loss, both players drink the value of their own card plus the value on the middle card.
   • On a Single Loss, that player drinks the value of his or her own penalty card, and the other player may distribute the drinks on the other two penalty cards to any player.
   • On a No Loss, neither player drinks.
8. Play continues from step 3 with the pair of players dealt the Twos from the Pairing deck, then those with the Threes, and so on.
9. Once the last pair has faced off, re-shuffle the pairing deck and deal it again.

Scoring

The number of drinks corresponding to each penalty card is left as an exercise, as it should depend on the players' tolerance, the drink, the duration of the game, etc.
For example, you may want to just remove everything over 5, or you may want to divide the numbers by two, or do something like setting a maximum number of drinks any single player can get at once (so a 'winner' may be able to distribute ten drinks, but not all to the same person). The face cards allow for some creativity -- for instance, the Queen may correspond to an Apple-tini, the King to the King of Beers, and the Jack to, well, Jack.

Analysis

The reason for playing sequentially (e.g. first the Aces, then the Twos, on down) is to allow players to observe how other players act, so that they can adjust their strategies accordingly; the pairs are kept secret to prevent players from discussing their strategy with one another beforehand (although one variant would be to allow this -- of course, with the understanding that lying is not only allowed but expected). The first round, it's basically a game of rock-paper-scissors, as no one will have seen their opponent play in the past (though they may know the player's personality), but it's likely that in subsequent rounds, snitches will be more likely to be punished (leading, perversely, to more snitches).

Variants

• Known penalty. The middle penalty card is face-up.
• Quick game. Pairs face off simultaneously rather than sequentially.
• Alternative pairs. Rather than Aces facing eachother, Twos facing eachother, it becomes more like a bracket -- first, the Aces face each other, then they each face the player with the Two of the same suit, who then faces the player with the Three of the same suit, and so on. This allows players to develop individualized strategies faster
• Random pairs.After each match, re-deal all of the pairing cards; the players with the Aces are always the ones to play. This works even if there is an odd number of players, and decreases the likely wait before players start showing up again.
• Modified penalty matrix. For instance, perhaps a No Loss allows the players to distribute the "blame" (drinks) to other players.
• Teetotaler version. There's no reason that you need to use drinks as the punishment -- it could just as easily be the "Prisoner's Dilemma Party Game". You can play with poker chips, with a cribbage peg board, with a Candy Land board, electric shock, hot peppers, whatever -- it just needs to be something that will incentivize players to want to win.

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