I'm extremely disappointed to learn that Firefox allows access to motion sensors by default and provides no option to make it ask for permission. It can only be disabled completely but this silently breaks legitimate uses like this one. This is a privacy nightmare. There is so much that can potentially be inferred from motion data, like user identity, mode of transport (maybe even location), what they're likely to be typing in the url bar or in an iframe, emotional state, a bunch of health information...

edit: Nice game, though. I wonder what it's made with. There seems to be a huge amount of generated shader code in the js. I wonder if that could be avoided.