Browser and itch.io

Melay is built for this. It is pure GDScript, so a web export needs no special setup.

Before you start

Your relay must be on HTTPS. A browser game cannot connect to a plain ws:// address. Deploy to Cloud Run if you have not already, then set Url in Project Settings > Melay to the wss:// address it gives you, and Mode to Remote.

Export

cd demo
godot --headless --export-release "Web" build/web/index.html

Do not open the result by double-clicking it. Serve it instead:

scripts/serve-web.py

Then open http://localhost:8000.

Upload to itch.io

Make a new project and set Kind of project to HTML.
Zip the contents of build/web, with index.html at the top of the zip.
Upload it and tick This file will be played in the browser.
Set the viewport size to match your game.

Or host it on the relay

The relay can serve your game itself, at /play:

cd demo && godot --headless --export-release "Web" build/web/index.html
cd .. && scripts/deploy-cloudrun.sh --with-web

This is the easiest way to test, because the game and the relay end up on the same address.

If the game will not load

A SharedArrayBuffer error. Your export has Thread Support turned on, which needs special headers. Either turn Thread Support off in the export settings, or serve the game with scripts/serve-web.py, which sends them for you. Melay itself never needs threads.

Nothing happens at all. You opened the file directly instead of serving it. Use scripts/serve-web.py.

It loads but cannot connect. Your relay address is ws:// and needs to be wss://.