Little models. Big ideas. Nothing to install.
Playable models from Scott E. Page's The Model Thinker — one page each. Scroll, drag, tap. Learn a model in five minutes without opening a stats book.
🟦🟧 Schelling · segregation
Mild personal biases produce dramatic collective segregation. The direct analog to Parable of the Polygons.
● live🚶 Random walks
The √t rule, the return-time paradox, drunk man vs drunk bird — the null model for streaks.
● live🦠 SIR epidemic
Three compartments, two rates, one number: R₀ decides whether an outbreak explodes or fades.
● live🔔 Normal / CLT
Watch bell curves emerge from any starting shape — and see the √n rule shrink the noise.
● live📈 Power laws
Rich-get-richer produces hubs, straight log-log lines, and 80/20 concentration.
● live🏔 NK rugged landscape
When decisions interact, hill climbing gets stuck. See why exploration beats greed on complex terrain.
● live🏺 Path dependence · urn models
Three urns, one coin-flip mechanic, three totally different worlds. Why QWERTY stuck and Silicon Valley is where it is.
● live🌐 Markov chains
The world forgets. Weather, brands, addiction, democracy — all chains that converge to π regardless of where they started. One-time fixes decay; only rule changes stick.
● live🎮 Life & Local Majority
Three rules for cells on a grid — and out come oscillators, spaceships, and universal computers. Then compare against the "boring" sibling that just freezes into clusters. Emergence in one picture.
● live🐦 Boids · three rules, one flock
You don't animate the flock. You write the rules for a single bird — then run many copies. Three rules (separation, alignment, cohesion), eight regimes (flock, swarm, mill, starling…), live polarization and rotation readouts. Turn one rule off and watch the whole illusion collapse. Hollywood's bats and wildebeest came out of this.
● live🎲 Entropy · surprise in bits
One number scores how unpredictable a distribution is — and the same number classifies every system into one of four fates: equilibrium, periodic, random, complex. Dial the odds, then meet all 256 elementary cellular automata.
● live🕸️ Networks · who knows whom
Same people, different wiring, different world. Add shortcuts to a village and watch six-degrees emerge. Play the friendship-paradox game — your friends really do have more friends than you. Then attack a scale-free network two ways and see why hubs are strength and weakness in one.
● live🎲 Game theory · edit a number, flip the game
A live 2×2 payoff matrix with every number editable. Nudge the Prisoner's Dilemma's betrayal payoff and watch it dissolve into a Stag Hunt. Then play 20 rounds of Repeated PD against five opponents — Tit-for-Tat, Grudger, Always Defect — and feel why one-shot logic fails under reputation.
● live🗳 Auctions & voting · the rules are the game
Four reasonable voting rules on the same 122 ballots pick four different winners. A three-voter Condorcet cycle shows the agenda-setter picks the outcome. Then flip to auctions: drag the Vickrey slider and watch "tell the truth" become optimal — and change one assumption to meet the winner's curse. The "reverse game theory" that won three Nobels.
Based on Scott E. Page, The Model Thinker (Basic Books, 2018). Source and Python versions on the parent repository.
