Unfinished. Thoughts? I was going for 'shiny metal' with the shading palette, but I'm not sure if it works.
[Edit] Aaand looking at it from another monitor now that this is posted, damn is that saturation cranked up. Apparently the color balance on the monitor I was using when I sketching this really sucks!
For reference I thought of the Boxer and what I have learnt and implemented in to this sprite over the years as there are some parallels to make I think which can hopefully help.
First one: It's far too saturated, and in retrospect quite simple. Details are done with 'linework' and lots of pixel-placing. Less understanding of the 'bigger-picture'.
Step 2 looked to reduce the saturation. Also generating some interest with features like the lights and a greater focus on lighting (albeit it doesn't understand it quite as well as it could). Still a focus on linework to give greebling and generate interest. Individual plates are 'drawn' and it is expected that this will make the ship look right (I want a plate, I know it starts here and ends here, so I just draw a line, right?)
Step 3 is current, and I think is the best version of the Boxer. The focus moves away from rigidly expressing detail with lines etc. and has faith in the creation of form and interest just through the lighting. Variances in lighting between plates works far more effectively than treating the whole ship as a more globular form with some lines drawn on top.
Basically I think it could be improved markedly just by trying to make the 'lines' inferred rather than explicit; and by some fairly simple work on adding some spot lights or small edge fins at junctures or something.
I would get a couple of layers dropped on over the top of this sprite and:
a) play about with the airbrush and lasso to soften some of the individual gradients (but introduce hard lines of delineation at shadows / edges). Go big; don't shirk and draw as boldly as you can. Delete if it doesn't work and start again. If it's not hard enough, but you think it's sort of right - duplicate this layer and multiply it.
b) refine with an overlay layer with some highlights / lowlights. 'Soft light' can work for this. If it's not bold enough, but it's sort of right - duplicate the layer and multiply it.