It's doesn't work. I see an error in console:
Uncaught TypeError: can't access property "VERTEX", xl is undefined <anonymous> https://html-classic.itch.zone/html/16342153/assets/index-53g21qnx.js:272</anonymous>
Weird, seems to work for most folks. If you feel like it, maybe try in a different browser if you have one handy (though it's a minimal experience so no worries if not)
