Great, with some problems
I wished this game could have been better than it was, although it was still really good. However it has a few too many problems.
First of all; having a lives system just won't do here. This is the kind of game that's all about trial and error. Having to push "reply" every three deaths is annoying, mainly because you have to use the mouse to click the button whereas the rest of the game you're at the keyboard. I know this sounds foolish to complain about but do this pointless boring thing about twenty times and you'll get frustrated, trust me.
However, the biggest problem was that although "going through a level half-blind" is a fresh new idea, it's not a very GOOD idea. Ultimately; it's a frustration more than an engaging concept.
But then comes the good parts. I still rate this game as high as I do because I like fresh new ideas, even the not-so-good ones, and I simply adore the visual style (although the animation does look a little too "tweeny" on the character when he's jumping.)
One more thing I like: you put into full practice the lesson of "don't make it too long" which was taught to us by Portal, the master of all puzzle games.
Like the game, want to see more stuff by you. More invisible character stuff? No, this concept needs to live no longer than it is born. But you are on the right track!