Rock Paper Scissors

Rock Paper Scissors: A Simple Game With Surprising Depth

Rock paper scissors (RPS) looks trivial, but it's a classic example of a zero-sum game in game theory. With a perfectly random opponent, the mathematically optimal strategy is to pick each option with equal 1/3 probability — any bias can be exploited over time. Against humans, however, psychological patterns emerge: people who just won tend to repeat the same hand, and people who just lost tend to switch to the hand that would have beaten their own previous move. Tournament players study these patterns to gain a statistical edge.

Beyond the game itself, RPS is used to teach basic probability, decision theory, and even Nash equilibrium concepts in economics classes — the mixed strategy of 1/3, 1/3, 1/3 is a textbook Nash equilibrium.