I was confused about what it was.
Then I saw that its sideways. Anyways, good work, nice attenction to detail, but theres a few details I don't like.
The smoke, after looking at it for awhile, looks more like black pitch coming out of the machines. It lacks more depth, and so where the huge robot's foot touches the ground it looks a bit off.
There's not much else I want to comment on, because I have those faults too in my drawings.
So good work, keep on keeping on!