Game theory your class plays, not reads.

• Prisoner's dilemma — two suspects, separate rooms

  Pairs choose silence or talk, a boss changes the payoffs, the same round is played again, and the room sees how it fell both times.

  In pairs · About 30 min · 2 acts

  Dominant strategiesRepeated games

  PlayingHow it plays, and how to run it
• Chicken — four seconds on a single-track lane

  Two cars closing on a lane with no passing place. Pull into the verge and the whole depot hears about it in the morning; hold the middle and hope they don't. Backing down is the worst thing that can happen to you — right up until neither of you does, which is the worst thing that can happen to either. Played twice, the second time with somebody in the passenger seat.

  In pairs · About 30 min · 2 acts

  Anti-coordinationNash equilibriumMixed strategies

  Try itHow it plays, and how to run it
• The stag hunt — one day, two ways to spend it

  A stag needs both of you on the ridge all day and the share that comes home is five suppers. A hare is three, it is yours alone, and you can take one at any point in the day. Neither choice is right by itself: what you should do depends entirely on what you think the person beside you is about to do. Played twice, the second time when being the one who stayed actually costs you four suppers out of an empty larder.

  In pairs · About 30 min · 2 acts

  Coordination problemsRisk dominanceNash equilibrium

  Try itHow it plays, and how to run it
• Battle of the sexes — one evening, two plans

  One free evening, two plans, and no way to reach each other before you set off. You would both rather be at the other's thing together than at your own alone — so there are two ways tonight works, you each prefer a different one, and the two of you politely deferring ends exactly as badly as both of you digging in.

  In pairs · About 30 min · 2 acts

  Coordination problemsNash equilibrium

  Try itHow it plays, and how to run it
• Rock, paper, scissors — two rivals and a contract

  Two rivals, twelve weeks of work. There is nothing safe to throw: whatever you would always play, the person opposite can beat. The board shows what this room actually threw, and then the room throws again having read it — which is the lesson, because a pattern anybody can see is a pattern anybody can beat.

  In pairs · About 30 min · 2 acts

  Zero-sum gamesMixed strategiesNash equilibrium

  Try itHow it plays, and how to run it

• Ten rounds in the pot

  Ten tokens, ten times. A token you keep is worth one to you; a token in the pot is worth half a token to every single person in the room. The pot is better off the more goes in and you are better off the less you put in, both at once — and the board builds the room's own curve as it plays, round by round, which is the thing a final number cannot show you.

  Up to 600 people · About 11 min

  Free ridingDominant strategiesRepeated games

  Try itHow it plays, and how to run it
• Three rounds, three partners

  Split ten coins or take them all, three times, against somebody you have not played yet.

  In pairs · About 40 min

  Repeated games

  Try it
• Twenty coins, take it or leave it

  One of you divides twenty coins; the other takes the split or refuses it — and refusing leaves BOTH of you with nothing. Three rounds against three people you will never play again. The room sees every offer it made, which ones died, and how many coins it destroyed to say no.

  In pairs · About 45 min · 3 acts

  Fairness normsCostly punishment

  Try itHow it plays, and how to run it
• Send it and see what comes back

  Whatever you send your partner is multiplied on the way over, and then it is entirely theirs — nothing makes them send any of it back. Round one is trust with nothing behind it: nobody knows a thing about the person opposite. Round two changes three things at once — the sides, the multiplier, and the fact that you now know them — and the debrief says so, because a board that moved for three reasons cannot be read for one.

  In pairs · About 30 min · 2 acts

  Trust and reciprocityRepeated games

  Try itHow it plays, and how to run it
• Two factories, one market, and the price you both set

  You and one rival make the identical crate and sell into the same demand, so the price is not yours to set — it is whatever the two of you produce between you. Make a lot and you sell a lot cheaply. The room sees where every market landed between what one seller alone would have made and what a price war would have, and what each of them earned for it.

  In pairs · About 20 min · 2 acts

  Imperfect competitionNash equilibrium

  Try itHow it plays, and how to run it
• One of you builds the factory first

  One firm commits to its production and cannot take it back; the other sees that number and then decides. Nobody forced anybody — but committing to a large run leaves the follower nothing better than a small one, and the theory says that is worth exactly double. Played twice, with the sides swapped, so everybody gets to go first.

  In pairs · About 25 min · 2 acts

  First-mover advantageImperfect competition

  Try itHow it plays, and how to run it
• Four boats and a bay that belongs to nobody

  Four skippers work one bay, which stands about twelve strings of pots before it stops coming back. Shooting five strings beats shooting two every single time, whatever the other three do — and if all four shoot two, every boat lands twice what it lands when all four shoot five. One boat hauling costs the others nothing; the second takes it off every other boat, the two who worked steady included. Then it is played again, the year the bay does not come back.

  Groups of 4 · About 19 min · 2 acts

  Common-pool resourcesExternalitiesDominant strategies

  Try itHow it plays, and how to run it
• Three cars on one forecourt

  You hold a good car, a fair one and a banger, and room on the forecourt for exactly one. The buyer is not being cheated — they genuinely value any car at half again what its owner does. They just cannot tell which is which, so they pay one price for the average of what is out there. Putting out your worst car beats putting out your best, every time, and an honest seller is paid an average that other people's bangers dragged down. Then the cars are inspected.

  Groups of 3 · About 19 min · 2 acts

  Adverse selectionAsymmetric informationDominant strategies

  Try itHow it plays, and how to run it
• Matching pennies — the game where you want opposite things

  One penny each, one call each, at the same moment. One of you takes the pair when the two calls agree and the other takes it when they differ — so for the first time in this catalog the person opposite you is not playing your game, they are playing its mirror. There is nothing safe to call: whatever you would always say, they can price. Called twice, the second time with the room's own record of how it called.

  In pairs · About 30 min · 2 acts

  Zero-sum gamesMixed strategiesNash equilibrium

  Try itHow it plays, and how to run it

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