Rock Paper Scissors
Play rock paper scissors against the computer — classic or Lizard Spock rules, with a live scoreboard, win streaks and a downloadable match record.
Pick your throw, or press R, P, S (L and V for Lizard and Spock).
Make your move to start the game.
- You
- 0
- Computer
- 0
- Ties
- 0
- Rounds
- 0
- Win streak
- 0
- Best streak
- 0
- Win rate
- —
Round history
- No rounds played yet.
How it works
Rock paper scissors (roshambo) is a three-move game with a perfect cycle: rock crushes scissors, scissors cut paper, paper covers rock. Identical throws are a tie. Switch to the five-move Rock Paper Scissors Lizard Spock variant and each move beats exactly two others and loses to exactly two others: rock crushes scissors and lizard, paper covers rock and disproves Spock, scissors cut paper and decapitate lizard, lizard poisons Spock and eats paper, and Spock smashes scissors and vaporizes rock. Ties are still only possible when both players throw the same thing.
The Random computer picks uniformly from the available moves, so over many rounds
every result trends towards one third wins, one third losses and one third ties (one fifth
each way in the five-move game). The Adaptive computer is the interesting one: it
counts every throw you have made, finds your most frequent one — breaking ties in favour of
your most recent throw — and plays the move that beats it, opening with rock before it has
seen anything. That is why humans lose to it: people are bad at being random and repeat
patterns. Random moves come from a seeded generator, so adding ?seed=42 to the
URL replays exactly the same computer throws. Scores, streaks and the round history are all
computed in your browser — nothing is uploaded, there are no accounts and no ads.
Frequently asked questions
What are the rules of rock paper scissors?
Rock crushes scissors, scissors cut paper and paper covers rock; the same throw on both sides is a tie. In the five-move Lizard Spock variant every move beats exactly two others: rock crushes scissors and lizard, paper covers rock and disproves Spock, scissors cut paper and decapitate lizard, lizard poisons Spock and eats paper, and Spock smashes scissors and vaporizes rock.
How do you win at rock paper scissors?
Against a truly random opponent you cannot do better than one third wins, so the game is only beatable against humans, who repeat patterns. This tool's Adaptive computer does exactly that: it counts your throws, takes your most frequent one (ties go to your most recent throw) and plays the move that beats it. Beating it means being deliberately unpredictable rather than favouring a move.
Is the computer's choice really random?
With the Random opponent selected, yes — each round it picks uniformly from the available moves in your browser, before it can see what you chose, so it cannot cheat. Add ?seed=42 to the URL and the throws come from a seeded generator instead, which replays the exact same sequence every time — handy for testing or for a fair rematch.