01
Each round, you and your opponent simultaneously choose to Cooperate or Defect. Neither player knows the other's choice beforehand.
02
Your payoff depends on both choices. The payoff matrix below shows points earned per round.
03
Play continues for the selected number of rounds. Highest cumulative score wins.
04
Your opponent is one of the real algorithms from Robert Axelrod's 1980 computer tournament at the University of Michigan.
// PAYOFF MATRIX
TIP FROM AXELROD'S RESEARCH
Rational self-interest suggests defecting every round. But the winning strategy across the tournament was Tit for Tat — cooperate first, then mirror whatever the opponent did last round.