Hi again. Sorry for the delay in replying - I was away for New Year's.
I'm still not sure why this is working. I've asked a few people with varying setups to try playing the game, and it works for them. I've now included a proper downloadable version on the game's page. Hopefully that works - if not, then I'm really sorry, and I'll make sure to look into it further during a bugfixing window I've got scheduled later in development.