I’ve made a ping-pong fully multiplayer game. It’s based on deterministic model and WebSockets.
You can check it here: https://rmg-clocats-dev.gbln.app/
Also I offer a ready-to use backend technology which you can use to make similar or more complicated multiplayer games.
Everything is open-source.
See source code of the game here: https://github.com/red-machine-games/clash-of-cats-game
And check out backend source code here: https://github.com/red-machine-games/goblin-base-server
Hope you’ll like it.