Concept art for Sven Olsen's starship combat game project (same as ship designs here
Some custom homeworlds, type variants, and fringe-case planet concepts (more general types can be seen here
). Some of these ideas are not totally (or even a little bit) original.
Rings weren't supported in the game engine at the time that these concepts were done, but they have since been added.
I'm just kidding with the Death Star. Though we do have Doom Stars.