The lighting is a little confusing..
The ground is as bright as it would be in daylight, yet it's a night time scene.
Also i'm not too sure why half the screen is taken up by a cross section of the underground.
Maybe this could be for game play purposes? (zombies crawling up from the ground).
if it isn't though, I'd recommenced cutting it back, or at least drawing in some skeleton bones or buried jewels to make it interesting. A wall of dithered dirt is not interesting.