Fun! I was sold right from the intro. Crouching behind cover feels intuitive and adds a lot to the gameplay. I would have maybe positioned the corsshair where mouse cursor is and added a visible laser sight to the gun instead, but that's just my personal preference, and I probably would learned to like the current implementation just as well, if I just played a bit more :--) Well done!
(The web version crashes often (on my Windows Firefox) but I'm sure the desktop versions work better.)