Very interesting. I liked to ride on the bats but maybe it wasn't intended?
Even if not, maybe you could explore it somehow.
I notice the music suddenly comes on when you die, and goes away when you leave the beginning areas. I wonder if you intended the music to play throughout, but instead placed a positional audio near the beginning of the level when you meant not to do it? Guess I'm not really sure what may be the cause, but I am guessing you didn't intend it that way.
I do notice the bats push you down into the ground until you kill them. Once (or maybe eve more than once), I was able to fall through the world, and had to reload the page to start over from the beginning.
I actually liked this game, it looks pretty good and the mechanics are actually working pretty well for the most part.
I think it could work, nice job on this game!