The game will play on an html5 canvas element and immediately I stumbled trying to understand the issue of scaling and size. This one remains 1280 by 720 (720p HD) but rescales to fit the available width on the current window within minimum and maximum limits.
I decided to try some other game engines and the tuorials for Kiwi.js yielded this result (use A-S-D keys to move).
It wasn't immediately obvious how to make it render on my intended game canvas, nor to control the scaling to fit with my web page, but there are a lot of setup parameters yet to be explored.
However this is running entirely on the client machine and it was not clear from documentation if Kiwi.js actually provides the functionality for web based multi-player games. Those will require a game engine of some sort running on the server!
I then found Isogenic Game Engine that has been going for a few years. Video tutorials are online. The documentation definitely says it will do multi-player games.
Tutorial number 2 got stuck on the
loading animation, but the first example file worked, and that looks just like how the tutorial was supposed to come out, so I'm going to work with this IGE for a bit and I will be blogging here how I get on.