This is a really good platformer. It took me a while before I figured out the control key (E) to open the portals (You might want to put the controls in-game, like in many other platform games).
The crouching issue was already mentioned below by Cookiecrumbled. I'm divided about the speed (You could ramp it up, but a lower speed seems fitting here). The atmospheric music and the animation is great.
Cheers,
M