Interesing
It's a good idea and a challenge.
Only a couple of thing that i can think of:
1) Since there seems to be very little difference in hitting a wall and a spiked area, i Would make it so the walls all have a slightly rougher looking edge to them to give them a more ominous look.
2) The pipes that blow air came into the game without real warning. That mght be something to mention. Or say that there are other things to look out for. I don't know.
3) I'm having some troubles with the difficulty of the challenge levels, but that might just be me lol
Anywho it isn't to bad. =3
-Review Request Club