The prisoner's dilemma tournament is over. There were a total of 21 entries. The winner is Margaret Sy, with a total of 39 points. 2nd and 3rd place go to rpglover64 and THE BLACK KNIGHT, with scores of 38 and 36 points respectively. There were some fairly intricate strategies in the tournament, but all three of these top scorers submitted programs that completely ignored the source code of the other player and acted randomly, with the winner having a bias towards defecting.

You can download a chart describing the outcomes here, and the source codes for the entries can be downloaded here.

I represented each submission with a single letter while running the tournament. Here is a directory of the entries, along with their scores: (some people gave me a term to refer to the player by, while others gave me a term to refer to the program. I went with whatever they gave me, and if they gave me both, I put the player first and then the program)

A: rpglover64 (38)

B: Watson Ladd (27)

c: THE BLACK KNIGHT (36)

D: skepsci (24)

E: Devin Bayer (30)

F: Billy, Mimic-- (27)

G: itaibn (34)

H: CooperateBot (24)

I: Sean Nolan (28)

J: oaz (26)

K: selbram (34)

L: Alexei (25)

M: LEmma (25)

N: BloodyShrimp (34)

O: caa (32)

P: nshepperd (25)

Q: Margaret Sy (39)

R: So8res, NateBot (33)

S: Quinn (33)

T: HonoreDB (23)

U: SlappedTogetherAtTheLastMinuteBot (20)

When I first announced the tournament, people came up with many suggestions for modifications to the rules, most of which I did not take for the sake of simplicity. Maybe we should try to figure out what rules will make it easier to write more effective bots, even if that would disqualify many of the bots already submitted to this tournament.

Maybe we should have a prisoner's dilemma meta-tournament in which we define a tournament-goodness metric and then everyone submits a tournament design that is run using the bot participants in the previous tournament, and then use the rankings of those designs.

Wait: does anyone know a good way to design the meta-tournament?