This is very good :D
I like the music and the graphics. Also the gameplay is nice.
There are some times when you can't see what is underneath, which makes it a bit frustrating when you fall and there are spikes. I feels unfair. And I would put some checkpoints. Also, the are parts when if you touch the ceiling you die unjustified, maybe because of spikes that are up.
How do you did the blood effect? That interests me a lot.
Great job guys! Very funny