I'm pleased to find that planet textures now work here on itch.io. Due to a path issue, all planets were previously black, but they were supposed to be neatly textured. There are textures for barren and volcanic planets, special textures for gas giants, and textures for habitable worlds - some with cloud cover, some without. 

These textures are also carried over to the star systems the planets are in, so that number of planets you see orbiting a star or binary star corresponds to the number of planets you'll find inside, plus the correct textures.