A very original idea for the challenge. Very well rendered - crisp whites and deep blacks. The triangle in the upper right corner should have been avoided and the border does nothing for me. Overall - a very clever submission - thanks for sharing it.
I really like the way this photo works; we see the foot of the person while the shadow tells the rest of the story. Nice crisp focus with good capture of highlights and good contrast on the shadow.
One of my top picks.