Just for some of those black lines you might be better using a dark brown, like on the legs maybe.  I'm not saying the piece should be devoid of black.  And yes, it looks better at 2X or 3X. 

Yeah, it has hasn't it?

The game is actually going to be played at a 2x scale, which brightens up the picture a hair.

I'll look into doing that colored outline thing, see if that goes any better.

I don't really know how to go about reducing colors, unless you're refering to the one on the right, which was made before I ever considered a palette a viable option. Now I'm quite happy working in a palette, so long as it has the colors I need.

This has been in the queue for a while.

I actually think it's a cool design for a robot, but there are too many colors, and at this size it's too dark.  Consider removing some of that black outline, and reducing colors.  I also think it could stand to be enlarged a little.