This website does not use WordPress - it doesn't load any resource with a WP-related name, nor it have any JS or CSS class name relationship (except for .elementor-* CSS classes on some elements in the homepage).
Looking at the bundled JS file, I can say that the page uses, for sure:
It seems that this website is not based on any of the ...
I've never used it but I have heard good things about Etherpad. The teacher must install and tweak the software; for the students the experience is visiting just another web site (and editing stuff). You can turn Etherpad into an IDE with Plugins, e.g. ep_codepad and ep_syntax.
That is a type of Collaborative real-time editor.
The static site generator, Eleventy, uses Browsersync to live-reload pages, however this is an NPM module, which means it falls outside your preferences.
Another static site generator, Jekyll, has an option to enable Guard-LiveReload from the LiveReload Project. There are also browser extensions you can install to force page reloads.
basically there are now a huge number of sites for selling games. Maybe you need some special examples. I can show as an example here is this site of free Mobile games https://free-slots-no-download.com/mobile-slots/ You can see how its elements are placed on this site, and in principle, all other solutions were used. Of course, I also recommend review ...