Love the consistence for the theme of the game, with the bat chirps for the menu selection sounds. Really sweet flying paths on those fellas, too! Definitely top notch mood setter menu. Nice music, too.
The gameplay's very cool and feels original! It does get a bit boring after a couple of levels I feel, so maybe the concept needs a bit of something more. It also feels a bit claustrophobic seeing so little around you, but I understand that's part of the idea.
Would've been nice to have some ambient music for the in game part!