Rock, paper, scissors — no longer just a game

The rules are simple: Two players count "1…2…3…Go!" and then offer up their hand in one of three ways: rock (clenched fist), paper (open, flat hand), or scissors (forefinger and middle finger form a ‘V’).  The winner is decided according to the rules that rock blunts scissors (rock wins), scissors cut paper (scissors win), and paper covers rock (paper wins).  If the weapons are the same, then the game is a tie.

Given the intransitive rankings, a player should try to feign randomness; a predictable strategy is beaten.  Appearing more random than your opponent is in fact the only dimension of competition.  Apparently many find this thrilling or at least humorous:

Rock Paper Scissors is evolving into something else entirely: a genuine, bona fide, almost legitimate sport…
    The World Rock Paper Scissors (RPS) Society – yep, there’s one of those, too – boasts 2,200 members. The winner of this year’s world championship was honored with a parade at Disney World. Simon & Schuster recently published an official strategy guide.
    "I can think of five bars in the Dupont [Circle] area where you can find a money game, $1 to $20," Mr. Simmons says. "It’s the equivalent of pickup basketball."
    Tonight [Friday], Fox Sports Net’s "Best Damn Sports Show Period" will feature an extended segment on October’s world championships, held in Toronto. A British-made RPS documentary film is due in January.

Read this account of gambit strategies; here are gambits in more depth, written by the reigning world champion, Master Roshambollah.  Here are some faking strategies.

Style often corresponds to personality:

Paper is subtle, the choice of intellectual, passive-aggressive types. Scissors are devious, a tool of controlled malice. Rock is between-the-eyes intimidation, preferred by beginners and players who have been backed into a corner.
    "People fall into patterns," Mr. Simmons [also known as Master R] said. "From my personal experience, women tend to open with scissors. There are some other tells I don’t want to go into. But I can see things in the shoulders and the forearm."

Here is the full story.  Here is the world championship web site, which offers T-shirts and books, and of course the exact rules.  Here is the on-line magazine.  Here is an essay on how to coach the game.  The game also has applications in evolutionary biology.

The bottom line: The game is interesting precisely because it is so difficult to be (or appear) random in critical moments.  And being random universally only brings you to the middle of the pack.  On the computational dimension of randomness, read this article.