Rock Paper Scissorsの使い方

Play rock paper scissors in the browser — vs computer or a friend, best of 1, 3, or 5.

What is Rock Paper Scissors?

Rock Paper Scissors (janken, the classic Japanese version) decides a two-way contest through simultaneous hand signs. Decidable runs it entirely in the browser, so you can settle decisions alone against the computer or with another person sharing the device. Wins, losses, and ties are tallied automatically, which keeps multi-round matches moving without pen-and-paper tracking.

使い方の手順

1

Choose a mode

Select "vs Computer" for solo play or "2 Player" when someone else is with you. Switching modes resets the current match but keeps the cumulative stats.

2

Choose match length

Pick best of 1, best of 3 (up to 5 rounds), or best of 5 (up to 9 rounds). Use best of 1 for "who does the chore", best of 5 when the stakes feel bigger.

3

Throw

In vs Computer, tap rock, paper, or scissors — the computer reveals its throw simultaneously and the outcome displays. In 2 Player, the screen splits and both players tap at the same time; results only appear once both have picked.

4

Advance the match

Press "Next" to start the next round. The match ends automatically when one side reaches the required wins. Running totals continue to accumulate across matches until you reset them.

A concrete scenario

Three family members deciding who washes tonight's dishes

Situation

Coin toss only handles two options. They want a way to pick one out of three and keep score across the month to spot who has dodged duty the most.

How it played out

On a single phone, two of them face off in 2 Player mode; the winner sits out. The remaining person then plays a round against the computer to represent the third seat. After two matches the person stuck with the dishes is decided. The cumulative stats go into a shared chat so end-of-month history is transparent.

ヒントとコツ

  • Computer throws are independent — no pattern recognition or streak-avoidance
  • Ties do not count toward the win target
  • Stats persist in the same browser between sessions
  • Use the reset button to clear cumulative counters

こんな時に便利

Solo tiebreaker when there is no opponent
Deciding chores at home
Settling small disputes during online calls
Group games where you need a quick 1-on-1 judgment

Common mistakes to avoid

  • 1Thinking the first tap in 2 Player mode gives an advantage — results are held until both players pick.
  • 2Expecting "best of 3" to end after a single win — a player needs two wins to finish.
  • 3Treating ties as losses in the stats — ties are tracked separately and do not count toward the best-of-N target.
  • 4Assuming the computer adapts — it does not; every throw is independently random.