You and an AI driver both need to pick a side of the road — left or right. There's no prize for picking a "better" side. You only score points when your choices match. The AI is watching your habits and slowly learning to expect what you'll do next. Can you settle into a convention together?
Pick your side of the road
This is called a coordination game, and it's one of the most common — and most overlooked — kinds of game theory situations in everyday life. Unlike the Prisoner's Dilemma, where players are tempted to betray each other, a coordination game has no temptation to betray anyone at all. Both players want the exact same outcome: to match. The only real challenge is figuring out what the other person expects you to do.
The classic example is driving on the left versus the right side of the road. Neither side is objectively better — the entire benefit comes from everyone agreeing on the same one. Economists call this an "arbitrary convention," and once a group settles on one, it becomes what's known as a Nash Equilibrium: no single driver benefits from switching sides alone, even if the other side would have worked just as well from the start.
In the game above, the AI opponent doesn't know any secret strategy — it simply watches your recent choices and leans toward whichever side you've picked most often, the same way real social conventions form. Early on, coordination is mostly luck, since neither of you has any signal to go on. But over several rounds, if you keep leaning toward one side, the AI starts to predict you — and matches become far more common. That's exactly how human conventions like language, money, and traffic rules emerged: not through a grand plan, but through repeated interactions that gradually converge on one shared habit.
Game theorists also study "focal points" — options that stand out for reasons outside the game itself, making them easier to coordinate on without any communication at all. Understanding coordination games helps explain why some social norms are surprisingly fragile (they could easily have gone the other way) while others feel so natural we forget they were ever a choice.
Pair up with a friend or family member. Without talking or making eye contact, both of you silently write down "left" or "right" on a piece of paper, then reveal at the same time. Repeat for ten rounds, and count how many times you match. Notice how your match rate improves once you both start noticing patterns in each other's choices — that's coordination forming in real time, just like the AI in the game above.
What is a coordination game?
A coordination game is a situation where players don't compete — everyone benefits when they all make the same choice, like which side of the road to drive on.
Why do we all drive on the same side of the road?
Neither side is inherently better — what matters is that everyone picks the same convention. Once a country settles on one, it becomes a stable Nash Equilibrium no one wants to break alone.
How does an AI "learn" a convention in this game?
The AI tracks which side you've picked most often recently and leans toward matching your most common recent choice, similar to how real social conventions form from repeated behavior.
Is a coordination game the same as a Prisoner's Dilemma?
No. In a Prisoner's Dilemma, players are tempted to betray each other for individual gain. In a coordination game, there's no temptation to betray — both players just want to match.