Game Design

why we don’t play “rock, paper, scissors, lizard, spock”

If you’ve seen The Big Bang Theory, you’ve heard of a game called “Rock, Paper, Scissors, Lizard, Spock”.  The TV show popularised Sam Kass and Karen Bryla’s expanded version of “Rock, Paper, Scissors”, which included two more hand gestures, “Lizard” and “Spock”.

Kass and Bryla’s original invention was titled “Rock, Paper, Scissors, Spock, Lizard”, which is more logically correct, but the game is more commonly known as “Rock, Paper, Scissors, Lizard, Spock”.

I’ll let Sheldon Cooper explain the rules of the game to you.

  • Scissors cuts Paper
  • Paper covers Rock
  • Rock crushes Lizard
  • Lizard poisons Spock
  • Spock smashes Scissors
  • Scissors decapitates Lizard
  • Lizard eats Paper
  • Paper disproves Spock
  • Spock vaporizes Rock
  • And, as it always has, Rock crushes Scissors

Why Don’t We Actually Play “Rock, Paper, Scissors, Lizard, Spock”?

From Sheldon’s description alone, it’s clear that one of the big reasons we don’t actually play RPSSL is that it’s far too complicated.  In “Rock, Paper, Scissors”, you have to remember 3 rules.  Add 2 more actions and you have to remember 10.

As versions of the game can be played for any odd number of gestures above 3, the number of rules you have to remember scales as follows:

n = (x2 – x) / 2

where n is the number of rules and x is the number of gestures.

Number of gesturesNumber of rules to remember

Given that many studies have shown that the capacity of our memory is storing somewhere between 4 to 7 things at a time2, it’s no surprise that we give up entirely with even a slightly more complex version of “Rock, Paper, Scissors”.

“Rock, Paper, Scissors, Spock, Lizard”. Image from: Sam Kass.

“Rock, Paper, Scissors, Lizard, Spock” May Be Cool in Theory, But Is It Fun in Practice?

Overly complex systems are difficult to grapple with, especially in games which are meant to be quick, like “Rock, Paper, Scissors”.  But to me, there is something else flawed about the game design of “Rock, Paper, Scissors, Lizard, Spock”.


This comes down to the reason for designing the game.

I invented this game (with Karen Bryla) because it seems like when you know someone well enough, 75-80% of any Rock-Paper-Scissors games you play with that person end up in a tie. Well, here is a slight variation that reduces that probability.

– Sam Kass1

Sure enough, the game delivers on its promise.  By increasing the number of possible moves from 3 to 5, it reduces the probability of a tie from 1/3 to 1/5.

There’s nothing wrong about this logic.  “Rock, Paper, Scissors, Lizard, Spock” is a great theoretical extension of the “Rock, Paper, Scissors” design, but it’s not a great game.

From here on out, we know it’s possible to create RPS versions for odd numbers of gestures.  While the idea of using the logic of RPS to develop versions with more and more possible moves is cool (see the 101-gesture version “RPS-101”), these versions are not anything new, playable or fun.

RPS-15, or “Rock, Paper, Scissors” with 15 gestures. Image from: David C. Lovelace.

Are Ties A Problem in “Rock, Paper, Scissors”?

The difference on the game design front is that Kass and Bryla tried to solve a problem that wasn’t really a problem with original “Rock, Paper, Scissors”.

If 80% of RPS games played with someone you know ends in a tie, that means that you’ll likely get to a win/lose situation in 5 games or less.

Sure, that means you get maybe 4/5 ties, but even then, with such a short game loop, it’s not frustrating or bad.  Conversely, this serves a main design principle of “Rock, Paper, Scissors”.


That’s because “Rock, Paper, Scissors” is about anticipation.  It’s about that moment you release your hand from a balled-up fist.  The ties, and more so the repeated ties, add to the drama, increase the stakes, and make the game more fun.  They make you look into your opponent’s eyes and try to suss out their next move.

Ties are not a problem with “Rock, Paper, Scissors”; they are actually a strength!

Rock-paper-scissors” (CC BY SA 3.0) by Enzoklop

In reducing the number of ties, “Rock, Paper, Scissors, Lizard, Spock” reduces the amount of anticipation.  It removes the tension that builds up when you throw out the same gesture as an opponent, and takes away the excitement of immediately playing again to break the tie.  It eradicates the moment of finally winning or finally losing.


The Lasting Impact of “Rock, Paper, Scissors” in Game Design

Game design is about solving problems, but we have to make sure we are tackling the right problems.  A beautiful theoretical solution does not necessarily mean a better game, and vice versa.

“Rock, Paper, Scissors” is an essential part of every game designer’s toolkit and every person’s childhood.  It is not only used on its own to break ties or decide who does the dishes, but can serve as the basis for systems in games such as combat mechanics.

Friction is necessary in games, because it leads to moments of resolution.  That’s why the simplicity and imperfection of “Rock, Paper, Scissors” wins, every time.

References Cited

  1. Kass, Sam. “Rock Paper Scissors Spock Lizard.” Sam Kass. Sam Kass, 4 March 2006. Web. 11 May 2020.
  2. Cowan, Nelson. “The Magical Mystery Four: How is Working Memory Capacity Limited, and Why?.” Current Directions in Psychological Science 19(1) (2010): 51-57. Web. 11 May 2020.

Additional References

  1. Warner Bros. TV. “The Big Bang Theory — Rock, Paper, Scissors, Lizard, Spock.” Uploaded to YouTube, 18 December 2013. Web. 11 May 2020.
  2. Lovelace, David C. “RPS 101: The most terrifyingly complex game ever.” – Comics, Music & Games!., 13 October 2006. Web. 11 May 2020.