Minecraft Classic
classic.minecraft.net
The 2009 version of Minecraft, free in a browser tab
Sandboxes & Simulators
The original open-source SimCity, rewritten for browsers
graememcc.co.uk
Rabbit hole · Best on desktop
Free, no sign-up · online since 2013
Graeme McCutcheon ported Micropolis, the open-source release of the first SimCity code, to JavaScript. You zone residential, commercial and industrial land, run power lines and roads, set the tax rate, then deal with fires, traffic and the occasional requested disaster.
It keeps the original's slow tempo, so a city takes real time to grow and you notice precisely which road you should not have built.
Keep going
Picked for a shared category and overlapping vibe, not for popularity.
classic.minecraft.net
The 2009 version of Minecraft, free in a browser tab
eater.net
Three rules are all a flock of birds needs
playgameoflife.com
Four rules, and cells that build spaceships anyway
keiwan.itch.io
Build a jointed creature and let it learn to walk
falstad.com
Build a circuit and watch the electrons move through it
rednuht.org
Random two-wheeled cars, bred over generations, on hills