The Evolution of Trust

Play:

Maximise Touch: tap to choose; everything is a discrete choice, no drag or gesture required · Keyboard: not required — played entirely by tap/click

About:

Nicky Case's acclaimed 2017 explorable explanation escalates from a single cheat-or-cooperate choice, to a repeated match against one opponent, to a full round-robin tournament of named strategies (Copycat, Cheater, Grudger), to an evolutionary simulation where a population of strategies rises and falls round by round. It's real Axelrod-style game theory, not a dressed-up quiz: 6,280 GitHub stars, 1,002 forks, translated into 30+ languages by volunteers, and still receiving commits as of December 2025.

The page ships with no mobile viewport meta tag, so a phone renders it at desktop scale by default — legible but smaller than it should be until you pinch-zoom in once. The 'continue' buttons also sit on an animated decorative background that occasionally eats a tap (confirmed on both touch and mouse), so a second tap is sometimes needed. Neither stopped a full run from completing on a simulated phone with zero console errors. Two bundled sound effects (a slot-machine cue and a UI click) were actually licensed CC-BY-NC and CC-Sampling+, not CC0 as the rest of the asset set — both were swapped for other CC0 sounds already in the project before hosting here.

Credits:

Made by Nicky Case, 2017. Published here under the CC0-1.0 licence. Source code. The author's own page for it.

Phone check: played a full run — title, intro, and into the tournament — on a simulated phone (390x844, real touchscreen taps) and desktop (mouse) on 7 Sep 2026; zero console errors, zero page errors, zero failed requests; no viewport meta tag found (renders at desktop scale on phones by default); two non-CC0 sound effects (CC-BY-NC and CC-Sampling+) removed and replaced with CC0 sounds already bundled in the project before installing

Tags:

game theory · explorable explanation · educational · simulation