Rock-Paper-Scissors-Lizard-Spock Game

November 20, 2022


I am a big Big Bang Theory fan. So is my wife. Her absolute favorite character is Sheldon Cooper. In one of the episodes Sheldon proposed an improved version of the rock-paper-scissors game. This version extends the possible moves to five(5). The additional two options would increase the possibility of win chances as it minimizes the chance of both players picking the same move.

I made a javascript version. Using a few emojis for the hand graphics. I made a very simple interface

Game logic

The game logic is pretty simple.

build gameboard

  get user move
  get computer move
  get win_or_lose
  increment round
  if (round equals max_round) goto display_winner
  goto play 

end game

To check who wins per round we need to know the rules of the game (taken from Big Bang Theory wiki).

  • 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

Here are the rules again coded in javascript.

function winOrLose(playerChoice, computerChoice) {

    if (
        (playerChoice === Hands.Scissor && computerChoice === Hands.Paper) ||
        (playerChoice === Hands.Paper && computerChoice === Hands.Rock) ||
        (playerChoice === Hands.Rock && computerChoice === Hands.Lizard) ||
        (playerChoice === Hands.Lizard && computerChoice === Hands.Spock) ||
        (playerChoice === Hands.Scissors && computerChoice === Hands.Lizard) ||

        (playerChoice === Hands.Rock && computerChoice === Hands.Scissor) ||
        (playerChoice === Hands.Spock && computerChoice === Hands.Scissors) ||
        (playerChoice === Hands.Lizard && computerChoice === Hands.Paper) ||
        (playerChoice === Hands.Paper && computerChoice === Hands.Spock) ||
        (playerChoice === Hands.Spock && computerChoice === Hands.Rock)
    ) {
        // player wins 


I love hash tables! They minimize code complexity. This is a great alternative to the code above.

const WIN_OR_LOSE = {
    [`${Hands.Paper}${Hands.Rock}`]: true,
    [`${Hands.Rock}${Hands.Scissor}`]: true,
    [`${Hands.Scissor}${Hands.Paper}`]: true,

if (!!WIN_OR_LOSE[`${playerChoice}${computerChoice}`]) {
    // player wins

The previous bit of code only handle win conditions, what if both players choose the same move? We test this even before testing win conditions,

function winOrLose(playerChoice, computerChoice) {
    if (playerChoice === computerChoice) {
      // show tie result  

Finally, we test if the game has ended. Whenever a round ends, we check if the game should end(finished 10 rounds). If yes, we calculate the game result and notify the user.

  function gameOver() {
    let [yourScore, pcScore] = score;
    if (games >= maxGames) {
      done = true;
      if (yourScore === pcScore) {
        gameResult("It's a draw!", "tie");
      } else if (yourScore > pcScore) {
        gameResult("You win!", "win");
      } else {
        gameResult("You lost!", "lose");

User interface

For the input, I made five(5) buttons with images corresponding each game move. When the game starts you are prompted to choose a move. When the player chooses a game move, it’s checked agains winning conditions and depending on the outcome computes the score.

rock-paper-scissors game buttons
Rock-paper-scissors-lizard-spock game buttons

Play the game. Enjoy!

By @codespud  
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