, with a more robust ruleset and improved tournament structure.

This tournament will have three rounds. In each round, all participants privately submit a single bot via Google form. Once all submissions are in, the bots are played against each other and all bots from previous rounds, and each participant earns points equal to the total points scored by their bot for that round. All bots are made public after the round is over.

Each round of play is a round-robin tournament where each bot plays each bot once. (Including itself.) Each match between two bots consists of a random number of games that could be anywhere from 1 to 100. (The match lengths are determined individually, so your program will have to play matches of many different lengths.)

Each game uses the traditional payoff matrix for the prisoner's dilemma, converted to positive points; double cooperate gets 2 points each, double defect gets 1 point each, cooperate-defect gets 3 points to the defector and 0 to the cooperator. At the end of every match, points are normalized to a match length of 1 so that programs do not end up with more points just for lucking into a longer match. (For example, if your program played a 12-game match and ended with 21 points, that's normalized to 1.75 points towards its final total.)

If someone wants to join the tournament late, they receive points for any round they missed equal to the lowest-scoring bot in that round.

Bots must be written in Javascript, and are limited to a maximum of 300 characters. They should be a function that returns 0, false, "d", or "defect" for defection and 1, true, "c", or "cooperate" for cooperation. For example, this is a valid bot:

async function(opponentSource, mySource, simulate, history, opponentHistory) {return "cooperate";} 

If a bot does not return a result for a game, either because it errored, or ran for longer than 1 second, or doesn't have a return statement, it gets 0 points.

If a bot does return a result but its opponent does not, that bot gets 3 points for that game, regardless of whether it cooperated or defected.

The exact code for the tournament can be seen on Github 

. The bots are run within a web worker within a browser while my internet connection is turned off, meaning they are fully sandboxed from each other. As such, there are no restrictions on what a bot may or may not do.

, terminating a worker does not terminate any child workers it spawned. A bot could create hundreds of infinitely looping child workers that will stick around even after that bot is terminated, lagging the whole tournament. If any bots do that I'll just disqualify them preemptively.)

The program with the highest final point total wins. If there is a tie, I will run a second tournament of the same structure that includes only the tied programs, repeating this process until there is a single winner. If this ends in a stable equilibrium of tied programs, I'll resolve to all of them equally.

I will be playing myself. I will finalize my own bot submissions before looking at anyone else's.

Side-channel collusion between players is against the spirit of this game; please don't do it. Your bots can collude with each other, but don't talk to other players and form a secret cooperation ring. This does not mean that every entry has to be a serious attempt to win. For example, it is acceptable to submit a bot for fun/chaos that only cooperates with other bots whose source code has an odd number of characters, but then it would be against the spirit of the game for some-but-not-all of the current players to be told about your submission in advance.

If you want to participate but are not familiar with Javascript, please don't submit potentially-broken code. Just describe to me what you'd like your bot to do in pseudocode (i.e. English, being very specific about exactly what it does and leaving no ambiguities), and I'll translate it into Javascript for you. Alternatively, we can set up a time to have a voice call on Discord, and I'll give you a crash course in the Javascript features you need for a challenge like this. Expect this to take 30-90 minutes.

. If you make a mistake or change your mind, you can edit your submission right up until the form closes.