Rock Paper Scissors is one of the most structurally fair games ever designed. Three moves, each beating one and losing to one, perfectly balanced by definition. No single throw has a built-in advantage. Both players face identical options under identical conditions. If you removed human behavior from the equation entirely, RPS would be the fairest game imaginable.
Human behavior is the complication. People are not random, which means the fairness of RPS in practice depends on whether the competitive structure preserves the theoretical balance or allows exploitable asymmetries to accumulate. This is where the sport's rulebook earns its existence.
The cadence is foundational. Both players must throw simultaneously on an agreed count, typically "Rock, Paper, Scissors, Shoot." If one player reveals even slightly later than the other, they've seen information they shouldn't have. This is the closest thing RPS has to a fundamental fairness violation, and it's why qualified referees exist. A trained referee watches both hands simultaneously and calls late reveals. In casual play, timing cheats are common. In sanctioned matches, they're penalized.
Illegal moves are less obvious but equally important. Rock Paper Scissors recognizes exactly three gestures: a closed fist, a flat open hand, and two extended fingers. Attempts to add additional gestures (the "dynamite" fist-and-index-point is the most common) are penalized, not because they'd win — they're not in the rulebook and therefore don't beat anything — but because they introduce ambiguity. Clear, unambiguous throws are the physical foundation of a fair match. A referee who cannot clearly identify which of the three gestures was thrown cannot determine who won.
The win-stay/lose-shift pattern documented in the 2014 Zhejiang University research raises a different fairness question: if human psychology makes players predictably non-random, and some players have studied those patterns while others haven't, is that fair? The answer is yes. Preparatory skill advantage is how every sport works. A batter who has studied a pitcher's tendencies has an edge over one who hasn't. That's not a fairness violation. That's competition.
The short version: RPS is designed to be perfectly fair and is kept that way by the rules around cadence, throw clarity, and referee authority. No throw is inherently stronger. No player has a structural advantage. The asymmetries that emerge in actual play are behavioral, not mechanical, and the competitive rulebook exists specifically to prevent the mechanical violations that would undermine the theoretical balance.