Interstellar Mercenary Oni Robot

Saw this conceptart on the web and thought the design is so cool. Wanted to give it my take. I never modeled anything mech related so this was pretty far out of my comfortzone. I really want to challange myself and get better at what I love.
Lots of trial and error. Got very frustrated sometimes, but I learned a lot along the way.
Part of my process can be seen in my Polycount sketchbook:
https://polycount.com/discussion/135750/sketchbook-rukasu/p2

I am still working on the character in the concept and might make a whole scene with both models in it.

Original concept is by Cg Ron:
https://www.artstation.com/artwork/Pm3l8y
https://www.artstation.com/cgron91