Hi MetalFox, nice work.
Theres's a lot of anatomy issues here: his right shoulder seems unhinged and separate from the rest of his body, his has no waist and that results in the legs being placed awkwardly. His thighs should be thicker then the lower half of the leg. His torso also seems to be too big.
I think you used an unecessary amount of colors for this. You actually used 19 colors, but there are some colors that you only used for a few pixels that would boost that up, keep on the look out for slips like that. Even with those in mind, I think you used too many without really thinking if each shade was necessary. Also, the shading seems sporadic... for example, on the torso, it's hard to tell what's going on, like you're trying to cram detail in, when you shoud be focusing more on suggesting shape. Also, you don't need to use a full range of colors to suggest detail, like in the ribcage. Using black makes him look like a zombie, when simply a lighter shade would do the trick.
I'm having a hard time trying to put my thoughts into words here so if you need me to clarify anything just ask, hope this helps.