A suggestion on controls: make it two for both hands. Right (upper row) ASD and left HJK (lower). Takes a while to get used to, but it's much more comfortable than the default.
this game has a huge potential - with few updates it would be enjoyable for very long time. but the "pause" key is needed immediately, without it it's 3/5
Penguins were better, and, besides that, there already is a game based on exactly the same concept... Flying squirrel and getting acorns. I don't remember its name though...