Thanks so much for your comment! :D It was a lot of fun to come up with the different scenarios of "Make Coffee, but Kaiju" ^^
We absolutely struggled with it as well, but managed to make it work by setting up a html file with the contents of https://github.com/godotengine/godot/blob/master/misc/dist/html/full-size.html and setting that as the "export shell" in the godot export settings. That said, there are several things not working in HTML5, such as GPU Particles (we has to re-do all particles as CPU ones <.<), some weirdness with how Images are held in memory and it also doesn't seem to want to run in all Browser/OS Combos, as we unfortunately only found out after the submission deadline.