Pondering other worlds, whether those be the distant worlds in our own universe, or the worlds we can enter through the stories of others.
...
Speaking of which, here are some worlds/stories that I like, in no particular pattern or order (though this is probably in need of some updating):
The Cosmere
Avatar: The Last Airbender
The Legend of Zelda
The Xenoblade Chronicles series
Ender's Game, Speaker for the Dead, and adjacent books
Project Hail Mary
The Remembrance of Earth's Past
Dune
Interstellar
Arrival
Inception
Tenet
Princess Mononoke
Castle in the Sky
Fullmetal Alchemist
Star Wars
...And probably a bunch of others I'm forgetting. This list is not comprehensive.
I did this once a long time ago, and Silh was the one who figured it out...but then the Shard updated, so it changed. So....who can figure out what shade of grey the SU reply boxes are?