Game Theory 101: The Strategic Models Worth Knowing

Some situations don’t have a single right answer — the best move depends entirely on what someone else decides at the same time, and they’re thinking the same thing about you. Game theory is the study of exactly that: how to make a smart choice when the outcome depends on someone else’s choice too.

This is a field guide to the most useful ideas from game theory — the kind that show up in negotiations, pricing, relationships, and group decisions, often without anyone ever naming them.

Prisoner's Dilemma: acting in your own interest can make things worse for everyone

Two people are arrested for a crime. They’re held separately and can’t communicate. Each is offered the same deal: betray the other and go free, while the other takes the full sentence. If both stay silent, both get a light sentence. If both betray, both get a medium sentence.

Here’s the twist: no matter what the other person does, betraying is always the better choice for you individually. If they stay silent, betraying gets you off completely. If they betray, betraying still gives you a lighter sentence than staying silent would. So the individually “rational” move is always to betray.

The catch: if you both reason this way, you both betray — and you both end up worse off than if you’d simply stayed silent and trusted each other. Two people acting in their own best interest land on a worse outcome than if they’d cooperated. That gap is the whole reason this is called a dilemma.

Nash Equilibrium: a stable outcome nobody wants to leave

Remember “both betray” from the Prisoner’s Dilemma? That outcome has a name. It’s called a Nash Equilibrium — you’re both stuck there, not because it’s the best outcome, but because changing your mind alone wouldn’t help either of you.

This shows up everywhere once you know to look for it. Think about two gas stations across the street from each other — they tend to charge almost identical prices. If one dropped its price, the other would just match it, so neither one bothers to move first. Or think about a fight where neither person wants to be the one to text “sorry” first. You’re both stuck in an uncomfortable standoff, because moving first feels like losing, even though someone reaching out would probably make things better for both of you.

Zero-Sum vs. Non-Zero-Sum Games: not every gain comes at someone else's expense

In a zero-sum game, the total is fixed. Whatever one person wins, the other loses — split a pizza, and every extra slice you take is a slice they don’t get. There’s no way to make both people better off at the same time.

Most negotiations aren’t actually like this, even though they get treated that way. In a non-zero-sum game, the total itself can grow or shrink depending on how everyone plays. Two business partners who trust each other and both invest can end up with a bigger pie than two partners who don’t trust each other and both hold back. The same principle shows up in relationships, friendships, and team projects too — showing up for each other grows what’s available to both of you, while both holding back shrinks it. Your gain doesn’t have to come out of their pocket — sometimes there’s just more to go around, or less, based on how you both behave.

The mistake is treating every negotiation like it’s a fixed pizza, when it might actually be a business you’re both still building.

Tit-for-Tat: the simplest strategy that keeps winning

The Prisoner’s Dilemma and Nash Equilibrium both assume you only play once. But most real relationships aren’t one-shot — you deal with the same coworker, neighbor, or friend over and over. That changes everything, because now your choice today affects how the other person treats you tomorrow.

In the 1980s, political scientist Robert Axelrod ran a tournament where dozens of strategies competed against each other in a repeated Prisoner’s Dilemma. Some were complicated, tracking history and trying to predict opponents. The winner was almost embarrassingly simple: start by cooperating, then just copy whatever the other person did last time. If they cooperated, cooperate back. If they betrayed you, betray back — once.

Tit-for-tat won not because it was clever, but because it’s hard to exploit for long and quick to forgive. It never starts a fight, it never lets betrayal go unanswered, and it drops the grudge the moment the other side comes back around.

Schelling Point: the answer everyone picks without talking to each other

In the 1960s, economist Thomas Schelling asked people a simple question: if you had to meet a stranger in New York City tomorrow, with no way to contact them beforehand, where would you go, and when? He expected wildly different answers. Instead, an overwhelming number of people gave almost the exact same one: the information booth at Grand Central Terminal, at noon.

Nobody coordinated on that answer. Nothing in the question said Grand Central was the “correct” choice. It just felt obvious enough that people could reasonably guess everyone else would land there too — which made it the safe bet, purely because it stood out from every other option.

This is called a Schelling point (or focal point): a solution people converge on without communicating, just because it’s the one that seems obvious to everyone at once. It shows up anytime people need to coordinate without talking — agreeing on a meeting spot, guessing what a group chat will order for dinner, or knowing to tip 20% at a restaurant, even though nobody ever agreed on that number out loud.

The Ultimatum Game: why "something is better than nothing" isn't how people actually decide

Two strangers are given $10 to split. One person proposes how to divide it. The other can only accept the split as-is, or reject it — in which case both people get nothing. If you only cared about maximizing your own money, you’d accept any offer above $0, since even a single dollar beats walking away empty-handed.

That’s not what happens in practice. Offer someone a small enough slice — say, $1 out of $10 — and most people reject it, even though rejecting guarantees they end up with less than accepting would have. They’re not being irrational. They’re paying a small cost to punish a deal that feels unfair, even when nobody’s forcing them to.

This changes how proposers actually behave once they understand it. A “rational” proposer, expecting a purely self-interested responder, would offer as little as possible. A proposer who’s played this game before knows a stingy split is likely to blow up the whole deal — so most real offers land much closer to an even split, not because people are generous, but because fairness turns out to be part of what makes a deal actually go through.

Game of Chicken: sometimes removing your own options is the winning move

Two cars are speeding toward each other. Each driver can swerve or hold their line. Swerve, and you avoid a crash but look like the one who backed down. Hold the line while the other driver swerves, and you win the standoff. Neither of you swerves, and you both crash — the worst outcome for everyone.

Unlike the Prisoner’s Dilemma, there’s no single move that’s always best here. Whether you should swerve depends entirely on what you expect the other driver to do — which is exactly what makes this game so unstable, and so relevant to real standoffs, price wars, and arguments where neither side wants to be the one who backs down first.

There’s a strange trick that works in this game: making it impossible for yourself to back down. If you visibly throw your steering wheel out the window before the other driver commits to anything, they can see you no longer have a choice. Now they’re the only one who can still avoid a crash — and a rational driver facing that choice swerves. You didn’t become braver. You just made backing down the only option left, and it wasn’t yours anymore.

This shows up in business constantly. Two competitors selling nearly the same product get locked into a price war neither wants: cutting prices further hurts both of their margins, but being the first to raise prices back up risks losing customers to the other. Whoever blinks first effectively “swerves” — and the other one wins the standoff. Businesses have their own version of the steering wheel trick. Imagine a company publicly announces: “We guarantee the lowest price — if you find it cheaper anywhere else, we’ll match it.” That’s a public promise. Backing out of it later would look bad and cost them customers’ trust. Their competitor sees that promise too, and realizes the company can’t afford to raise prices first without a real cost. So the competitor ends up being the one who backs off instead. Or think about negotiating for a used car. You tell the seller your final offer and start walking toward the door. That’s the same move — you’re showing them you’re genuinely willing to walk away, not just bluffing. If they want the sale to happen, they’re the one who has to cave and meet your price.

Tragedy of the Commons: shared resources die when everyone takes "just their fair share"

Imagine a lake that four fishing families share. Nobody owns it, so nobody can stop anyone else from fishing there. Each family reasons the same way: “If I catch a few more fish this year, it won’t really change anything for the lake as a whole.” They’re right — individually. But all four families think exactly the same thing, every single year. A few years in, the lake is fished out completely. No family made one big destructive decision. Everyone made a small, individually reasonable one, at the same time as three other people making the identical choice.

This happens anywhere a resource is shared but not owned: an office kitchen nobody restocks, a group WiFi plan that keeps getting maxed out, groundwater pumped by every farm in a valley during a drought. Taking a little more, or cleaning up a little less, never feels like the moment that ruins it. It’s everyone doing that at once that does.

This is different from the Prisoner’s Dilemma in one important way: there’s no single other player to blame, and no one moment where the damage happens. That’s why it’s so hard to stop once it starts. By the time the lake is empty, there’s no single decision anyone can point to and say, “That’s what caused it.”

First-Mover vs. Second-Mover Advantage: sometimes going first wins, sometimes waiting does

“Move fast and be first” is common startup advice. So is “let someone else prove the idea, then do it better.” Both are right — just in different situations, and mixing them up is an easy way to make the wrong bet at exactly the wrong time.

The deciding factor is usually whether the market runs on network effects. If a product only gets valuable once enough other people are already using it — a marketplace, a social app, anything where you need your friends to join too — being first matters enormously. Once someone locks in that early lead, a better competitor showing up later usually isn’t enough to unseat them, because leaving means convincing everyone you know to leave with you.

Flip the situation, and the advantage flips too. If the idea itself is unproven — nobody’s sure customers actually want it, or how to build it well yet — being first mostly means paying to find that out. The first company absorbs the R&D risk, the confused customers, and the early bugs. A second company gets to walk in once the category already makes sense, with a cleaner version and none of the scars.

The Winner's Curse: winning an auction is sometimes proof you overpaid

Imagine bidding on a jar of coins where nobody actually knows the exact amount inside. Everyone in the room guesses. Some guess a little high, some a little low — that’s normal, nobody has perfect information. The jar goes to whoever bid the most.

Here’s the catch: winning doesn’t just mean you guessed well. It means you guessed higher than everyone else in the room. Out of a group of reasonable, slightly-off guesses, the winning one is specifically the most optimistic one — not the most accurate one. The auction doesn’t reward accuracy. It rewards whoever was most confident, which is a very different thing.

This is why company acquisitions so often disappoint, why sports teams regularly overpay for a star free agent, and why the highest bid in a house bidding war is rarely a bargain. Whoever wins wasn’t necessarily the one who valued the thing most accurately — they were the one who was most willing to believe it was worth the most. The fix isn’t to stop bidding. It’s to bid the value you actually believe it’s worth, and treat winning as a reason to double-check your math, not celebrate.

Putting it together

Here’s the set, in one place:

None of these guarantee you’ll make the right call in the moment — they’re patterns worth recognizing while you’re still in the middle of one. The next time a negotiation stalls, a shared resource feels like it’s disappearing, or you find yourself the highest bidder in a room full of guessers, there’s a decent chance you’re standing inside one of these ten games without having named it yet.