The Princess Bride strategy takes its name from the film's famous "battle of wits" scene, where Westley (as the Dread Pirate Roberts) talks Vizzini into a poisoned-goblet guessing game and wins not through cleverness but through having already prepared both cups. The lesson most people take from that scene is that outsmarting someone requires preparation before they know the game has started. The lesson that applies to Rock Paper Scissors is slightly different.
Vizzini's fatal error isn't that he tries to out-logic his opponent. It's that he treats the game as a pure information problem — one he can solve by reasoning hard enough — when the actual game was already decided. He's reasoning about probability distributions while missing that the underlying setup has already been resolved. In competitive RPS, the equivalent mistake is spending so much energy trying to predict your opponent's next throw that you lose track of your own tendencies and start producing patterns you didn't intend.
The Princess Bride strategy, as applied to RPS, is this: decide what you're going to throw before the count starts. Commit to a gambit or a single intended throw before your opponent has a chance to read your decision process. The moment you start the count undecided, you're reasoning in real time, which produces both visible tells and predictable patterns. Pre-commitment removes the decision from the throw.
This runs counter to the intuition that staying flexible is better. Players who decide during the count believe they're incorporating last-second reads on their opponent. Sometimes they are. More often they're producing the behavioral noise of someone who didn't have a plan — the hesitation micro-expressions, the slightly late reveal, the throw that arrives half a count behind the rhythm. These are readable and exploitable.
Pre-commitment doesn't mean rigidity. It means showing up to each throw with a clear intention, executing it cleanly, and then re-evaluating based on what just happened before the next count starts. The decision happens in the gap between throws, not during the count itself. Keep the decision process out of the throw. That's the whole strategy. Westley would approve.