How Our Hosted Worlds Work

Your own world on the internet that friends can join at any time — without anyone having to set up a server. That's the idea behind our Hosted Worlds, and in this article I'll show you what really happens behind the "Play" button in the portal.

The heart of it all is the WorldHost: a small service on our server that manages worlds. Each world runs in its own Docker container — fully isolated, with its own save file, its own memory limit and its own CPU cap. When nobody is playing, nothing is running: the world sleeps, the container is stopped, and it costs no resources.

When someone clicks "Play" in the portal, here's what happens: the WorldHost first checks whether you're allowed to join at all — for password-protected worlds, the password is checked before the world is woken up, so nobody can spin up someone else's world just by attempting to join. Only then is the container started, the world loads its save file, and you receive a short-lived join token for exactly that world. Meanwhile, the portal shows you the "Waking up world…" status.

Once all players leave the world, it goes back to sleep after a while — the save is written, the container stops. And if you'd rather continue playing your world locally, you can download the save and upload it again later: the save of a Hosted World is the same as that of a local game.

The whole thing is deliberately built small: no Kubernetes, no cloud magic — one server, Docker, and a service that starts and stops containers. For a family project, that goes surprisingly far. How far exactly, and what such a server costs, is a story for the article about our VPS.