loading from file does work afaik, yeah. If you're trying to open the game in a mobile browser, you can just find the index.html file and, if your file explorer of choice of has the option, open it with your browser. Otherwise, depending on the device, you probably need to type something like file:///(filepath ending with index.html) as the url. That's how it works on my tablet, anyway. And that's assuming opening the index.html file actually works, apparently even the backer version has issues with that now.