A very simple chat-game made in Godot Engine (exporting with WebAssembly) with a very minimal Nodejs websocket server (and static serving of the game files).
The server is by no means scalable, it is just around 100 lines of simple javascript, and I didn't even know javascript at that time!
I'm currently hosting it here
There is a Dockerfile, but you need to build the godot project outside from it first (because godot cli build command wasn't stable enough in 3.x versions)