Concept:
Pinback - Love the outworldly dystopian feel.
regularryan as a close second, this background looks just like a lonesome, slightly creepy roadside should.
Playability:
Cassiebsg - Very nicely detailed, I can easily imagine playing a rat in this location and interacting with the bars, the straw, the water dispenser, the cage door etc. Would love some additional details hinting what kind of a room the cages are in (a pet shop? a lab? a home rat farm?).
Artistic execution:
VampireWombat - If lightened up a little so you could actually see what is in the picture, it is an enchanting and slightly melancholic view. This would work beautifully as a background for an abstract, fairytale-ish game.
And I second what Pling! said, it was a great theme lorenzo and I'm glad it ended with an equally great turnout.
That pit immediately gave me prince of persia chills 
Hey you're right! It never occurred to me, but these pits must still linger somewhere in the long forgotten scars that nightmarish game left on my elementary schooler's psyche :>