Prisoner's Dilemma

Canonical game in which rational self-selection into defection leaves both players worse off than cooperation.

Specifications & Metrics

Flood and Dresher built the game at RAND in 1950; Tucker named it and framed the prison-sentence payoffs.
Defection strictly dominates cooperation, yet mutual cooperation pays both players more than mutual defection.
Repeated play lets cooperation survive through reputation and retaliation, as Axelrod's tit-for-tat results showed.