Pick rock, paper or scissors and see if you can outsmart the computer. Play single rounds or best-of matches, switch on the smart AI that learns your patterns, or try the five-move Rock Paper Scissors Lizard Spock.
You0
Best of 3 first to 2
Computer0
✊
Make your moveChoose below or press a key
✊
Your stats
Round history
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How to use the Rock Paper Scissors
Pick a game: Classic (rock, paper, scissors) or Lizard Spock (five moves).
Choose a match length (best of 3, 5 or 7, or endless) and the computer: Fair random or Smart.
Click a move or press its key (R, P, S, L, V or 1-5). The computer reveals its move after the countdown.
Win the round if your move beats the computer's. Equal moves are a draw and don't count toward the match.
First to win the majority of rounds wins the match, for example 2 wins in a best of 3. Your stats update after every round.
Who beats whom
In the classic game each move beats exactly one other move and loses to one. In Rock Paper Scissors Lizard Spock each move beats two moves and loses to two, so draws happen less often (1 in 5 instead of 1 in 3 when both players choose at random).
Move
Beats
Loses to
✊ Rock
Scissors (crushes), Lizard (crushes)
Paper, Spock
✋ Paper
Rock (covers), Spock (disproves)
Scissors, Lizard
✌️ Scissors
Paper (cut), Lizard (cut)
Rock, Spock
🦎 Lizard
Spock (poisons), Paper (eats)
Rock, Scissors
🖖 Spock
Scissors (smashes), Rock (vaporizes)
Paper, Lizard
In the classic game, only the first three rows apply and only against rock, paper and scissors.
Fair vs smart computer
Fair picks every move with equal probability using the browser's cryptographic random number generator. Over many rounds you can expect to win, lose and draw roughly a third of the time each in the classic game; in the five-move game it's about 40% wins, 40% losses and 20% draws.
Smart builds a simple model of how you play: it counts which move you usually choose after each of your previous moves (a first-order Markov chain), weighs in how often you pick each move overall, and notices if you tend to repeat a move after winning. It then plays a move that beats your most likely choice, and still plays randomly about one round in five so it isn't fully predictable. The "Your moves" bars show the same habits it sees.
Tips to beat the smart computer
Avoid patterns like rock-paper-scissors in order or always repeating your last move.
Don't stick with a winning move. Repeating after a win is one of the most common human habits.
Balance your moves. If one bar in "Your moves" is much longer than the others, the computer will counter it.
Use "Play a random move" now and then to see how a truly random player does against it.
Frequently asked questions
What are the rules of rock paper scissors?
Both players pick a move at the same time. Rock crushes scissors, scissors cut paper, and paper covers rock. If both players pick the same move, the round is a draw and is played again.
How does Rock Paper Scissors Lizard Spock work?
It adds two moves so each move beats two others and loses to two others: scissors cut paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors cut lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and rock crushes scissors. The variant was invented by Sam Kass and Karen Bryla and made famous by the TV show The Big Bang Theory.
Is the computer cheating?
No. The computer picks its move before it looks at yours. In Fair mode its move is completely random using your browser's secure random number generator, so in the long run you should win, lose and draw about one third of the time each in the classic game.
How does the smart AI work?
Smart mode remembers which move you tend to play after each of your previous moves and how often you use each move overall. It predicts your most likely next move and usually plays the move that beats it, with some randomness mixed in. If you play truly randomly it can't beat you, but most people have habits it can learn.
What does best of 3 mean?
A best-of-3 match ends as soon as one player wins 2 rounds; best of 5 needs 3 wins and best of 7 needs 4. Draws don't count, so a match can take more rounds than its number.
Is there a winning strategy?
Against a perfectly random opponent, no strategy can do better than an even split. Against people it's different: a 2014 study of players at Zhejiang University found a 'win-stay, lose-shift' tendency, where winners often repeated their winning move and losers often switched to a different move. The Smart computer looks for habits like these.