To answer my own question: reflect.js is missing from the zip-file I uploaded. D: The site responds with a 403 error for missing files. I hadn't checked what 'make bundle' produced...
So, I updated the game's description with instructions to get the missing stuff filled in, for any intrepid game testers among you...
Now that the game jam is over, I fixed this. You can now 'enjoy' my 'game' a lot easier. :)
