Rock Paper Scissors
Play Rock Paper Scissors against the computer. Track your wins, losses and ties.
How to play
- Click 🪨 Rock, 📋 Paper, or ✂️ Scissors to make your move.
- The computer picks its move randomly — no patterns to exploit.
- Rock beats Scissors, Scissors beats Paper, Paper beats Rock.
- Your running win/loss/tie tally updates after every round.
- Click "Reset score" to start a fresh tally.
Play Rock Paper Scissors against the computer. The computer picks randomly. Track your win rate across as many rounds as you like.
How it works
Rock Paper Scissors is a classic hand game for two players. In this online version you play against the computer. Choose Rock, Paper, or Scissors by clicking the corresponding button. The computer simultaneously makes its own random choice, and the winner is determined by the standard rules: Rock beats Scissors, Scissors beats Paper, Paper beats Rock.
The computer selects its move using a random number generator with equal probability for each option, so there is no pattern to predict or exploit. Each round is statistically independent. Over many rounds, each outcome (win, loss, tie) should occur roughly one third of the time.
The game tracks your wins, losses, and ties across the session, letting you see how closely the results converge on the theoretical equal distribution over time. Streaks of wins or losses are normal short-run variation and do not indicate a true advantage or disadvantage.
This tool is also useful for demonstrating probability concepts: run 30 or more rounds and observe how the win percentage approaches 33 percent as the sample size grows.
Worked example
Demonstrating the law of large numbers
- Play 10 rounds and note how far your win percentage is from 33 percent.
- Continue to 30 rounds and check again.
- Continue to 60 rounds.
- Record win, loss, and tie percentages at each checkpoint.
- Observe that percentages converge closer to 33 percent as round count increases.
A hands-on illustration that short-run streaks even out over many trials.
Common mistakes to avoid
- Believing a losing streak means the next pick should change strategy, when each round is independent and previous outcomes have no effect.
- Thinking the computer uses a pattern that can be exploited; the selection is random with no memory of prior rounds.
- Interpreting a short-run win rate above 50 percent as skill, when variance over a small number of rounds commonly produces such streaks by chance.
Key terms
- Random number generator (RNG)
- An algorithm that produces unpredictable outputs; here it selects the computer's move with equal 1/3 probability for each option.
- Tie
- A round where both players select the same option; neither player wins or loses.
- Law of large numbers
- A statistical principle stating that as the number of trials increases, the observed frequency of each outcome approaches its theoretical probability.
Frequently asked questions
- Does the computer cheat?
- No — the computer picks rock, paper or scissors with equal probability (Math.random). There is no lookahead or pattern detection.
- What beats what?
- Rock beats Scissors, Scissors beats Paper, Paper beats Rock.