Pretty cool concept, and nice art and sound. My complaint is that a lot of the levels feel very samey, and then there's quite a difficulty spike with the level pictured below. The art of the start and end points also look kinda strange, and the vents look like you can only move horizontally/vertically through them (depending on the orientation of the sprite). I do like that the alpha of the count down timer increases as it gets closer to zero.
