Helm thanks a bunch for the extra thoughts and feedback. I will definitely keep it in mind - the "shines" as such are in their mainly as a way to help the shapes stand out, a role that is traditionally played by lighting. I think possibly simpler textures and some dynamic flat (as in not filtered or averaged) lighting COULD be a decent substitute, and I will definitely experiment with that as I continue the 3d-pixel quest. The problem with lighting objects that are this simple is you lose a LOT of control over what you get - if I paint my lighting on I can ensure that the mech looks the way I want it (be that bad or good) from pretty much any angle. I guess it's a control thing (as is the whole discipline of pixel art?). However, the end quality of the design is more important than self-indulgence!
One technical/aesthetic gripe I do have about using "real" lighting in games is that except for the highest powered systems there are a lot of compromises that have to be made with the colors you use. As pixel artists we love to mix blues and yellows with our shadows and highlights to get more realistic or at least more believable lighting on our shapes and forms. Generally speaking this is a limitation on computers that is hard to control/exploit. You can tint highlight colors or display colors pretty easily, but it is very hard to get something like blue shadows working in-game. On something like the DS I imagine it is similar to very basic OpenGL in that you really only have a couple of lighting options (without writing some kind of amazing assembly anyways); ambient, diffuse, and specular. The only one that can affect shadow color is the ambient piece, but if you bump up your ambient to a blue then it has a direct affect on how dark your shadows can be. Basically, as a pixel artist the kind of affect i'd want is a real ramp of colors that are used for shaded areas, but if you want dark shadows you have to set black, and if you set blue then your dynamic range is severely limited. Diffuse and Specular lighting on a system like the DS are generally limited to either flat faces or averaged values; averaging the normals on something like this would be absolutely hideous, and the specular lighting has a tendency to wash out colors as it is just an added tone across all colors on the palette (you can't have dynamic specular on something like the DS that knows to use a certain ramp on the yellows and different one on the reds).
Something that I'd like to try is writing my own blending function that just does a lookup on a ramp instead of a straight addition (like if value of shadow is between 20 and 40 then look in spot 3 on the "red" ramp). This is kind of how cell shaders work, but they generally don't do it on a per-texel basis.
My point is (and probably this was self-evident but whatever!) that I think people are better at coloring and lighting things (especially on hardware like the DS) than a computer chip is. Thus the chunky, hand-lit approach. Unfortunately some of my forms weren't popping like I wanted so I added the shines in (sometimes in somewhat unlikely locations) to help those shapes read better. My other concern is that generally, in-game, these bots will be max maybe 150 pixels tall, and frequently maybe 60 pixels tall. I need to make sure that all the shapes and forms still pop and read at those resolutions.
Anyways I hope that helps in some way, not saying the bot is perfect but more that he is the result of a lot of compromises that I am still debating myself!