Rock Paper Scissors

Free, no sign-up, plays in the browser. This opponent is not random — it watches how you change your throw after a win and after a loss, and tells you what it found.

Why it beats most people

A computer that threw at random would win exactly a third of the time, forever. This one does better, because people are not random. Researchers at Zhejiang University ran rock paper scissors as a long-running experiment with hundreds of players and found a pattern they called win-stay, lose-shift: after winning a round people tend to repeat the throw that just worked, and after losing they tend to move on to something else — most often the throw that would have beaten the one they just lost to.

So the opponent above keeps a small table: what you threw next, given what happened last round. Once one of those entries leans, it plays the counter. The line under the score tells you which lean it found — you can watch yourself get read, and then break the habit on purpose.

The rules, in one line

Rock breaks scissors. Scissors cut paper. Paper covers rock. Same throw is a tie.

Want a version with actual decisions?

One throw against one throw is a coin flip dressed up as a game — the only skill in it is pattern-breaking. Rock Paper Scissors War keeps the same three throws and gives you a hand of them to divide across three fronts at once. You see how many cards your opponent committed, never which ones. Take two fronts and you win.