Oh you want C&C do you!? Hehe, ok.
Your first version had redundant shades. Especially the 3 lightest ones. Current version seems to fix that, though I haven't checked it's actual palette. I don't like the dark theme at all. Not enough contrast. Your pragmatic lineart usage is hurting readability. This sprite is small, you don't have room to outline every major shape in this char. Attempt actual volume shading, not mere shape-outlining with a little bevel highlighting.
At least you have moved away from being completely monotone with that purple helmet shield. Previous version's pal was a simple monotone ramp with no virtual shifting. Liking the jetpack.
Ok, so:
-Try a better hue shift with your current palette
-Lighten it up
-Shade more dynamically
-Get away from your inclination to outline everything. Outlines are overrated.
PS. When I Google "Achromat", I get a bunch of camera lenses. What do you think an achromat is? Why not plain astronaut?