Domo arigato mr rubble robotOoo... wait that doesn't make any sense. I'll translate for my addle brained self:
the mesh seems constructed well. I do have questions aobut the mechanics of the hips and how they would actually work in real life, but hey its for a game, as long as you can rig it, and it looks great, who cares?! Not that many people will ask "but would that really work in real life?" when they see it ingame.
The textures and renders seem a bit dark on the mesh. Might be coming from the renders or the smoothing groups? Hard to tell You seemed to pack a buch of detail on the skin in areas no one will easily see. WHile that is great, it also takes texture space away from the important areas. The blue armor plating looks like it lacks detail while the nuts and bolts seem to oooze detail. The detail could be there and I just can't see it because the renders lack an ambient light?
It might help if you did some renders with the texture at 100% self illum?
I think you did a great job painting the textures, but to give that them a little extra pop, I would play around with the brightness and contrast. I think part of the darkness came from drawing on a white background? If you did start with white as a background you might want to choose something a bit different. Like the main color of the model you are working on, or maybe even black or dark grey.