Consider the RC2014 https://rc2014.co.uk I think it hits a bunch of these points. Also don't overlook the SpecNext https://www.specnext.com -- both have very active communities.
No frameworks or libs. Vanilla.js, raw Canvas and requestAnimationFrame. In this version, they are symmetric with slight random variations. No reason they have to be though.
Emacs, and Chrome dev tools. The build environment has jslint set up in it too. I can't recommend enough js{lint|hint}ing all your code. None of the stuff in the sim is super tricky.
If my first game hasn't finished (It wasn't a complete stalemate yet but they have stocked up a lot of fighters and bombers) when I get home I'll try that! I find zero-player games fascinating, especially ones such as this.