Heeey again.
First off I APPROVE of the subject matter and what you're getting at--this is cool, could potentially be cooler.
As for the NES vibe from the palette palette, yeah, I can still see that.
When you're restricted to mono palettes or anything for a while, you might think that it's a formula you have to follow.
It's something you have to break out of gradually.
Studying real life references, etc. helps.
Let's break this down:
Your value is pretty good but could use more obvious ramps. The small amount of colors you have is good to start off with tho. Another important thing: even though it's muscles, you still need to define the major planes of the head with those few colors.
Hue: you've actually shifted this but not enough to be noticeable. With the red light, keeping it generally mono makes sense but it still has to be visible or it's inevitably going to look like the NES palette.
Saturation: is a whole other ballgame, not even touched here as far as I can see, it's all max saturation. Fleshy objects usually have smaller desaturated highlights, saturation around the midtones and into the shadows, which fall off into desat. again.
What Mathias said about the expression is true and a pretty common hurdle. In trying to draw in the anatomy you forgot the big picture, the gesture. In this case it's the facial expression. You want menacing, go lower brows, wider jaw. Try grimacing in a mirror. Feel that expression.
This edit demonstrates both those things:
Lines from the WIP so you can see that more clearly.
Adding in subtle angles/perspective works really well and adds to that. This edit might be overdoing that, depends on the art direction really. If you're going for this retro Saturday morning cartoon look (which it looks like with the character design) straighter angles could work, but you see the point?
Implementing more cyberpunk elements into the muscles is a cool opportunity, one I tried to take in that edit.
Also played up the ape-like quality.