Unfortunately many people have reported this black screen but I am unable to reproduce it my end. Perhaps it is to do with it running in browser, that's a good point! At least an executable file would provide a more useful error message that would help me track down the error much more clearly. I'll look into that! That's a very good idea.
Strange that the buttons didn't work for you, there has been 1 other report of this too. Maybe it's a keyboard thing? That it only supports say 4 simultaneous keys? If you were to try it on a different keyboard it may work?
Thanks for the suggestion of also providing a downloadable, I'll get on that!