It's been quite a while since I worked on sci-fi figures, so these have been an interesting new challenge!
First, it is fun to paint something that is not greens or earth tones... and also some metals. I used the Reaper Blue, Brown and Gray liner paints. To lighten them, mixing in seafoam green, light flesh tones and light blues gives the mixes just enough variety to create subtle transitions and color shifts.
Otherwise, it is very likely that endless seas of "grey" would get very boring!
I believe that all of this is from Puppets War, made by DreamForged Games
Working within grays has been so important over the years, I even made that part of the Painting Pyramid. As you might imagine, that episode was called "Shades of Gray". It was one of 5 'color theory' videos that I did, similar to this:
I will be trying to finish off one of these on Twitch once I get that figured out!c