Rock-paper-scissors-lizard-Spock

A diagram explaining the outcomes of the game

Another diagram, displaying clockwise from top: Scissors, Paper, Rock, Lizard, Spock

The normal form matrix of Rock-paper-scissors-lizard-Spock. Rows represent available choices for player 1, columns those for player 2. Numbers in cells show utility (payoff) for player 1, player 2.

Rock-paper-scissors-lizard-Spock is an expansion of the classic selection method game rock-paper-scissors. It operates on the same basic principle, but includes two additional weapons: the lizard (formed by the hand as a sock-puppet-like mouth) and Spock (formed by the Star Trek Vulcan salute). This reduces the chances of a round ending in a tie (from 1/3 to 1/5). The game was invented by Sam Kass with Karen Bryla, as "Rock Paper Scissors Spock Lizard".

The game was mentioned in four episodes of The Big Bang Theory. According to an interview with Kass, the series producers did not ask for permission to use the game, but he was later referenced in an episode in the fifth season for which he thanked them on his website.

Rules

The rules of Rock-paper-scissors-lizard-Spock are:

• Scissors cut paper
• Paper covers rock
• Rock crushes lizard
• Lizard poisons Spock
• Spock smashes scissors
• Scissors decapitate lizard
• Lizard eats paper
• Paper disproves Spock
• Spock vaporizes rock
• Rock crushes scissors

There are ten possible pairings of the five gestures; each gesture beats two of the other gestures and is beaten by the remaining two. As with the original rock-paper-scissors game, if two players pick the same gesture, it is a tie. The original rules (rock beats scissors, scissors beats paper, paper beats rock) remain the same.