How to Build a Multiplayer Lobby in Unity with Socket.IO

Building a multiplayer lobby is where most Unity real-time projects fall apart.

Not the networking part — that's the easy bit. The hard part is everything around it: players joining and leaving mid-session, the host disconnecting and taking the room with them, a player's phone screen locking for 30 seconds and losing their slot forever. Most tutorials stop at "connected". This one doesn't.

This is a complete walkthrough of building a production-ready lobby in Unity using

MIT licensed. Socket.IO v4 only. WebGL verified. Zero paid dependencies.

What's the hardest part of multiplayer lobbies you've had to solve? Host migration, latency compensation, or something else entirely? Drop it in the comments.