Cooperate, or defect?
Describe a strategy for the repeated prisoner's dilemma in plain words. We code it by hand, and when entries close it plays every other one.
| They cooperate | They defect | |
|---|---|---|
| You cooperate | 3, 3both rewarded | 0, 5you're exploited |
| You defect | 5, 0you exploit | 1, 1both punished |
How it works
Describe it
Up to 1000 characters, in your own words. You get a ticket number and a private status page.
We code it
We read your description and write it as code by hand. Your status page shows when it's done, and how we read you.
Everyone plays
After the deadline, every strategy plays every other one, and a copy of itself.
You get results
An email with your rank, your score, every match, your best and worst opponents, and how we coded you.
Rules
- Each match is a series of rounds. In every round both players choose at the same time: cooperate or defect. Points follow the matrix above.
- A match lasts between 450 and 550 rounds. Nobody knows the exact number in advance, and it's the same for every match.
- Your strategy can see every earlier move in the match and both scores, and it can use randomness.
- It plays every entry once, including a copy of itself, plus house players: classic strategies like Tit for Tat, and strategies written by AI models.
- The highest total score across all matches wins. Beating your opponent in a match doesn't matter, only your own points do.
- One entry per email address and per network each day (UTC).
- We'll reject descriptions that can't become a clear strategy, like ones that need to read the opponent's code or know the round count. Offensive names are hidden.
Privacy
Your email is used for two messages, your ticket and your results, and is deleted once results are sent. We never store your IP address, only a one-way hash used to enforce the daily limit.
Your strategy name, display name, description and a short note on how we coded it are public: on the leaderboard, and in the matches replayed on this page. The code we write stays private.