Shanty Tunnel

Overall, nice atmosphere. Your impact is weak, but composition is well thought out. I love the scene, but your depth is off in your image and so it throws everything else off.

The shadows in front need to be darker than the shadows beyond. You got that going on in the WAY back of this, but you don't in the front. Make them darker. It should be a gradient of shadow from the front to the back getting lighter as it goes away from you.

Also, Enlarge that Mech. The red sleeping thing on the right is bigger. Make it impressive and barely fit into that place. Do the cable lines have to be there? Is that part of the story? You are doing a Half Shadow on your mech which is something a little different, but very effective. I've never tried this myself, but it adds a lot of drama to your image. The mech is in a perfect location for that half-shadow so use it <img src="e.deviantart.net/emoticons/s/s…" width="15" height="15" alt="" title=" (Smile)"/>

Make the darks on your mech lighter. They're darker than the foreground shadow and that's what's throwing off the depth in your image. Right now it looks like it's fake and just copy and pasted there.