multisim

MultiSim

This is a proof of concept to show what it could be like to have a fully multiplayer version of WebSim (a browser where an LLM generates the webpages).

multiplayer-sim.mp4

How is it multiplayer?

• There is presence so you can see what pages other people are on.
• If you are on the same page as someone else, you can see their multiplayer cursor
• Multiple people can see a webpage stream in together
• There is multiplayer chat so you can talk to other users

This is demoware / a proof of concept. I wrote this over a weekend and decided that I don't want to flesh it out, but it is architecturally interesting so it is worth sharing.

Getting started

Create a .env.local file with the following:

OPENAI_API_KEY={Your Key}
WEBAPP_URL=http://localhost:3000
NEXT_PUBLIC_PARTY_KIT_HOST=localhost:1999
NEXT_PUBLIC_PARTY_KIT_URL=http://localhost:1999

bun i
bun dev

How does it work?

• The main shell of the app is a Next.js app that you can host anywhere.
• There is a partykit room that is powering the multiplayer features.
• Right now there is an in memory cache of pages inside of the room.
• All ai generation is handled on the partykit room. This lets llm generation get de-duped across clients.
• There is a very small postMessage protocol for transmitting things like cursor positions between the iframe and the parent

What is missing?

There isn't any long term persistence of the pages or account management. Right now there is only a single hardcoded room as well. If you want to actually scale this you will need to be able to shard people into different servers. You really want the concept of a "party" or a "universe" where people can all jam on things together.

Why did you stop working on this?

I started working on this because it would be a fun proof of concept. Once I proved to myself that I knew how to build it I stopped because I don't really want to build out a full fledged websim competitor.