WARNING :
It seems godot has some trouble with exporting 3D games in html5. Or maybe it's itch.io. Just wait a one or two minutes when the game starts and when you load your first level, mute the page if you don't like this horrible sound, and don't panic, it should be working fine :) Else you can get the windows/mac/linux versions or the godot-project that I uploaded on this page ;) Enjoy!