Thanks! Gave it another try and now I was able to finish several levels, yay :) By the way, my game uses a similar mechanic!
As for the feedback, I think camera is the main issue. First of all, it took me forever to figure out that you can rotate it, and even then it turned out to be almost useless since you lose track of what keys do what. Maybe if e.g. [W] did a forward move with respect to camera orientation (as opposed to world orientation), it would be easier to navigate?
Anyways, nice concept & level design, beautiful atmosphere, good job!