Play Rock-Paper-Scissors-Spock-Lizard Online
Rock-paper-scissors-Spock-lizard is a five-gesture extension of the classic three-gesture roshambo game. RPSSL adds two additional moves, Spock and lizard. The rules are:
Rock crushes scissors and lizard
Paper covers rock and disproves Spock
Lizard eats paper and poisons Spock
Scissors cuts paper and decapitates lizard
Spock crushes scissors and vaporizes rock.
See the history of the game and mathematical trivia below the RPSSL simulator.
In RPSSL, each gesture beats two gestures and is beaten by the remaining two gestures, thus, none of the five symbols has an advantage over the others. The probability of two players making the same move in a random game is only 1/5 (20%). On average, in a series of random rounds, the probability that Player A wins is 2/5 (40%), and that of Player B is 2/5 (40%). This is shown in the table of outcomes below.
How to Form Spock and Lizard
About the Pentagram Diagram
Rock → Scissors → Lizard → Paper → Spock → Rock → ...
Rock → Lizard → Spock → Scissors → Paper → Rock → ...
Trinomial Probability Distribution for Wins and Ties
P(a, b, t) = [n!/(a!b!t!)](0.4)a(0.4)b(0.2)t
Examples: In a game of 5 rounds, the probability that A wins twice, B wins twice, and once tie is
[5!/(2!2!1!)](0.4)²(0.4)²(0.2) = 480/3125 = 0.1536
In a game of 10 rounds, the probability that A wins 4 times, B wins 4 times, and twice tie is
[10!/(4!4!2!)](0.4)⁴(0.4)⁴(0.2)² = 32256/390625 = 0.08257536
Other Expansions of Roshambo
Of course, the challenge in developing and playing such games is inventing enough distinct gestures, remembering them, and remembering the other gestures they beat. One enthusiast has created a rock-paper-scissors game of 101 gestures, most of which require two hands to form.
© Had2Know 2010