Those are good ideas about the flap action. If we were to make a full game out of this, that would definitely be a priority to work on. There's so much room for improvement there, but it would take time to try out ideas and get it right.
As for the death sound, I think that's apt. Something simple with the piano but that still conveyed a feeling that a bad thing happened. Now that you mention it, maybe this game might be better without a failure state. The obstacles are mostly there to give you a reason to move around, hopefully without being difficult.
Thanks for your feedback!