how it works
payoff is a game theory lab you can play in a minute. No jargon, no homework — every game is a real experiment about people, dressed up as something fun to lose at.
the loop
One grammar for every game. Learn it once:
- predictCommit to a number, a move, an offer. Skin in the game before you see anyone else’s.
- playSeal it. Now you wait with everyone else — the countdown is the ritual.
- revealThe crowd unlocks at once. You vs. tonight’s strangers vs. the classic study. That’s the payoff.
the coins
Coins are earned, never bought. There’s no checkout, no top-up, no cash-out. You can’t send them to a friend and a friend can’t send them to you — they don’t move between players at all.
Your vault is just a stack of receipts: every stake, every win, every forfeit, in order. Proof of what happened, not a wallet.
This is a lab, not a casino.
provably fair
“How do I know the game didn’t peek at my guess?” Fair question. Here’s the whole trick, in plain words:
When you seal your guess, we don’t store the guess — we store a hash of it: a scrambled fingerprint you can’t run backwards. That hash is public before anyone reveals.
So nobody — not the crowd, not us — can peek at your number or quietly change it after the fact. When the round reveals, every guess is checked against its fingerprint. The math either matches or it doesn’t.
Commit first, reveal later. No trust required.
the lab
Every game doubles as a live re-run of a classic experiment. You’re not just playing — you’re a data point, and the reveal shows you how your table compares to the ones in the textbooks.
Guess ⅔ of the average. Everyone thinking one step ahead cancels out — the smart answer keeps shrinking. Almost nobody plays it to the bitter end.
Offered a split, take-it-or-leave-it. Textbook says take any crumb. Real people torch the deal to punish an insult — and they did in 1982 too.
Axelrod ran a tournament of strategies. The winner was the simplest: be nice, retaliate once, forgive fast. Can real humans out-play Copycat?
what’s coming
Two-Thirds is the first game, not the last. Same one-minute loop, more ways to (mis)trust each other:
- the ultimatum split
- the public-goods commons
- the trust ladder