one thing is the uac establishing bases on other planets and i guess cities, even though we barely see the actual city part of d3's mars city
but i wonder about cities in space, like bases and ships in space where people live in and do city things, while they look at the stars and walk their space dogs
2016 i think had one or two multiplayer maps taking places in large ships in space (maybe one was underwater, but the space one also had portals to hell)
and i already talked about the potential of doom having more space stuff beyond Mars Core, like the Cultist ship unused from Eternal or those concept arts for planets












