Here's a quick NPA edit, I didn't have time to properly pixel it but the general ideas should still come across.
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Basically there's big issues with volumes and hues. You're trying too hard to preserve the lineart, so in the colring there's very little flow in terms of light/dark, everything is very washed out and consequently the only thing that jumps out are the outlines. Balance and flow are something that should be present in the value and hue of the piece as well as the general composition.

Positive and negative space are present in your lineart but you've colored it in such a way that there is none, it's all very flat. If you were to take out the linework this piece would be nearly indecipherable. Hue and value can and should be used to help communicate the space that you are trying to portray. After the initial sketch I believe this is the most important step in any finished work and should really be taken care of first, before you even start thinking about detailing. Look how much the picture pops when you add a bit of variety, without making any drastic changes to your character design.

Actually the contrast is correct: the more distant objects are lower contrast and lighter. It gives a very good sense of atmosphere. Although I agree that the whole thing is probably a bit too noisy if you were going to use this in a game. Sometimes large areas of texture are best summarized with a carefully few placed patches of detail rather than showing every single rock and pebble, brick and leaf. That way, as Emtch said, you will be able to direct the player's attention to the most important things on the screen.

Pixelling aside I see a major problem with composition. 50% of your piece is blank space and the other half is made up of tiny condensed details. There's no reason for microscopic characters and pinprick text when you have that much empty space to work with. Even if this is a fake for a game (which I'm not sure if it is?) composition and proportion should be the first issue that gets addressed.

I don't agree that you should break your character into animated and non-animated pieces. This is not how things move - the entire body is involved with even a seemingly simple action. Animate the whole body as a rough sketch first and then decide which pieces you can re-use, if any, when you do the final pass. Otherwise I promise you'll get very stiff and lifeless animations every time.

Awesome as always, Arne... I haven't played Z but from judging by the screenshots, it's got this weird sort of Spaghetti Western or possibly even American Civil War flavor mixed into it, except that's genuinely futuristic and not simply garden variety steam-punk. From a conceptual standpoint it seems that there's a lot of untapped potential there.