great artowrk, i love the lots and lots of details, the colours and the light effects.
What programm did you use? And how long did that picture took to finish?
i may give only one advise: the fire of the mech in the backgraound looks too liquid in my opinion. I don't know how this bullet-shoot-fire is called in english, but cause i can see empty shells falling on the ground i guess he shoots some kind of projectiles and for this kind of weapon the fire looks a little bit too much like drops of liquid ^^