Run kxb yourself
The community edition is a public repository: a browser-based multiplayer world with an event-sourced backend you can stand up on your own machine in an evening.
Checked against the sources on 2026-08-30
What you are getting
kxb is a browser-based virtual arcade: a chill 3D lounge, mini-games, a level editor, and spaces you invite people into with a link. The community edition is the same application we run, minus our infrastructure, our brand details and our paid-product campaigns - built from the private tree by a sync tool, so it stays current rather than drifting into a fork.
The stack: Next.js on Bun, Supabase (Postgres + realtime + auth) as the backend, an event-sourced core - the event log is the source of truth and read models are projections - and Three.js for the worlds. No game server: multiplayer runs over realtime channels with client arbiters.
The art is CC0 but heavy, so the repository does not carry it: kits by Kenney, Kay Lousberg and others are fetched per docs/assets.md, which credits every author properly.
From clone to lounge
Install the toolchain
Bun (the runtime and package manager), Docker (for local Supabase), and the Supabase CLI. macOS or Linux; Windows works via WSL.
Clone and install
Where: github.com/kappaxbeta/kxb
git clone, then `bun install` at the root. The workspace packages resolve locally.
Fetch the art
Where: docs/assets.md in the repository
The document lists each CC0 pack, where its author hosts it, and where it unpacks to. A few generated packs rebuild locally with the listed `bun run` scripts.
Watch out: Skipping this leaves you a world of placeholder dummies. The doc exists so the artists get their credit and their download counts.
Start the backend and the app
`supabase start` brings up local Postgres, auth and realtime in Docker; `supabase db reset` applies every migration. Then `bun run dev` - the app expects the local stack and finds it on the standard ports.
Make yourself the first admin
Sign up in the app, then insert your email into `backoffice_admins` against your own database - the migration explains the one-line SQL. The repository ships no seeded admin because it does not know who you are; everyone after you is added through the backoffice itself.
Before you put it online
Replace the placeholder imprint details in the legal shell - the fields are marked and the comments say why shipping someone else’s name is worse than shipping none. Then the chapters of this handbook take over: the legal shell your site needs, and what to check before you promote it.
The traps
- Running against the art-less tree and concluding the renderer is broken.
- Deploying with the placeholder imprint still in place.
- Expecting our deploy scripts - the community repo ends at your hosting choices on purpose.
- Editing generated files that a `bun run` script owns; the script wins the next sync.
Where to go from here
- Deploy it: the poor man’s stackThe hosting half this guide stops short of - one cheap box, under €10 a month.
- The repositoryCode, README, and the docs folder.
- docs/assets.mdEvery art pack, credited and linked.
- The XP editor guideHow games are made once the world is running.
This is a map, not legal or tax advice - and an honest one about how it was drawn: the Germany guide was written by a person who walked the route; most other countries were drafted with AI against the official sources and have not yet been walked by someone who did it. Laws change. Every guide carries the date it was last checked and the sources to check it yourself - and if you have been through one of these routes, your corrections are exactly what this handbook wants.