Command and Conquer

It's been awhile since I played this game, and needed to draw some symbols. The two pictures were drawn months apart.
The Nod one is just a sketch while on break at work while it was still cool enough to draw. Nod is a group of terrorists who believe that all must harness a certain type of radiation for the good of all. Their strength is in numbers, and a customizable walking mech that slaughters lots of things.
The GDI one is me trying to draw an actual picture. While nobody could tell by looking, I'm starting to draw much faster. All those sketches I've done in the last few months I guess. GDI's strength is power, and a large tank called The Mammoth Tank.

Since the Nod one is so old, and it was a sketch, you don't need to comment on it if you don't want to.
Since the GDI one is an actual attempt at art, critique away. I'll list what I know I did wrong, of course. The leg should be thinner and more angular, the left foot tip is too broad, the right is too narrow. The neck and the head should be thicker, extending up about a fourth more then it is. I should have used my ruler to make the parallel hatching.

I think I'm getting better at parallel hatching, and I had to use it here. I was using just some number two pencil because I lost my sharpener, and the edge of the pencil lost it's sharpness before I started shading. This was all drawn in the car. The Nod picture took about 4 hours, the GDI picture took 2.