By the way the first 2 times I played I could not hear anything, neither music nor sound effects (I think it was not my computer). Only after reloading the browser and entering again it worked fine. I hope it helps you.
Thanks for playing and commenting! The leaderboard is a free addon from SilentWolf really easy to implement, all my score games have it now :-) And I'll look into the sound problem, but I don't really know where to start... Anyway, I'm glad you had some fun!
