micropolisJS
graememcc.co.uk
The original open-source SimCity, rewritten for browsers
Sandboxes & Simulators
The 2009 version of Minecraft, free in a browser tab
classic.minecraft.net
Instant · Best on desktop
Free, no sign-up · online since 2019
Mojang put the original creative-mode build of Minecraft on the web for the game's tenth anniversary. Thirty-two block types, no crafting, no monsters and no survival, just a wide flat world, a hand, and a shareable URL that lets nine other people build alongside you.
The block palette is small enough that you stop optimising and simply build, which is what the game felt like before it acquired systems.
Keep going
Picked for a shared category and overlapping vibe, not for popularity.
graememcc.co.uk
The original open-source SimCity, rewritten for browsers
dan-ball.jp
The falling-sand classic, still updated after fifteen years
eater.net
Three rules are all a flock of birds needs
playgameoflife.com
Four rules, and cells that build spaceships anyway
pmneila.github.io
Two chemicals, two dials, and every pattern in nature
brm.io
Two dozen physics scenes you can grab and throw about