I think it would be interesting to see a planet where a dense fog makes it appear as though everything is in black and white.
With enemies hiding in the fog, your only chance of survival, to spot their glowing eyes before they leap.
Different LIGHTING EFFECTS on the Planets! Nice! Depending of the Sun of it's Own Biome it would make the Colors, Lighting and everything be UNIQUE.
I think an once habitable city filled with buildings and skyscrapers would be freakin' amazing, or perhaps indeed a roarin' twenties film noir styled planet, with a bunch of detective sidequests.
Both of these sounds amazing if you bake them together, and what I'm SEEING in front of me is really, really scary. A plus would be if the monsters are very, very high-tier, with the main way of defeating them being to trick them into jumping into traps and other stuff like that. Maybe some ruins from an not-so-ancient civilization too, with clues strewn about in logs and such to what happened to them?
