I found this out the hard way too, unfortunately the game doesn't work on phones (at least, it doesn't work on Android phones, IDK if iOS is different).
The Android web viewer thing can't run javascript, and a lot of mobile browsers don't let you open locally hosted html files (I guess for security reasons maybe). I assume the reason it's marked as playable on mobile is because theoretically it should be able to be played in any browser, it's just that mobile browsers have a Thing about locally hosted html files.
I have been able to open it and play it in the Opera mobile app on Android, but unfortunately it doesn't load any of the images or sound files, and it occassionally has bugs that I suspect I wouldn't run into on computer. I haven't run into the exact issue you're describing, though, so I dunno if that's any help.