There's a name for the colours used in these sprites, particularly on the far-left - the desaturated yellows and greens. They work fantastically to convey the appearance of metal and they compliment the sprites that also use grey tones for the same purpose, so we have weapons and helmets that all look a different class but have the same base and purpose. That paired with the great cyan range makes these units my favourite of the lot.
Wow this is a very cool :)