Seriously... no barren worlds in Sins? I mean, like the moon, with no atmosphere.
This came to mind as I was making a map of the Solar System with Venus, Mars, and Mercury. Mars is obviously a desert, Venus a cloudy planet (another thing we should have, that I had to settle with desert) and Mercury is a barren planet, but I had to use Volcanic.
I also wish we had planetoids or "dwarf planets" in Sins. Like Pluto, Ceres and Eris. Instead, I had to settle with Ceres as an asteroid and Pluto as a way to large ice planet.