Colour palette...
There's a couple of things i'd suggest to make this piece pop a little from the screen, right now the viewers angle in the scene is not very exciting, there's a lot of dead space that's not doing anything or telling us anything about this world or what goes on in it.
I've tried to write this next bit out a couple of times but it's late and i'm having trouble articulating what i want to say, instead i did a little paintover on this piece, messed around with the perspective in Photoshop, added a couple of things, it's not perfect but hopefully you'll see what i'm too tired to say right now:
http://www.newgrounds.com/dump/item/b84283a983bd6e71eed94cc0f1bf5a28
Somethings i would like to point out, one: in any factory or anyplace with a lot of heavy machinery things are normally marked out in bright yellows, the yellow/black markings are a staple of places like this, things/areas you should be aware of, etc, you should try to include thgis in your design, detasails like that can help make clear what sort or setting a place is.
two) Scale, right now in your piece we have no idea how big anything is, these mechs could be no bigger than a shoe for all we know, put some objects in whose scale people know and can subconsciously use to get an idea of how big this place is.
3) The colour palette, even in my paintover i didn;t have mch time to go into this, but right now it needs a little more variety, things that you want to bring attention to could do with brighter or more noticable colours, things that dont need less saturated/ muted colours so they can sit in the background better.
Hope this doesn;t sound like me being mean, i'm just trying to help out a little. This is just me throwing in my two cents, disregard if you want.