Here's my draft at refactoring the tag system. Includes all old tags and a good quantity of new tags.

== GENRE
18+ -- mature, adult themes
Alien, incl other planets, alien worlds
Arena
Beast, incl animals in general
Crossover
Fandom, incl fanfic
Fantasy
Horror
Military
Nation
Paranormal, incl  Supernatural, Superhuman
Psychological
Realistic
Romance
School
Sci-fi
Slice of Life
Steampunk
Tabletop
Vampires
Western
WorldBuilding

== ERA -- the gist of the time period
Ancient
Apocalyptic
Historic
Medieval
Modern
Future
Post-apocalyptic

== TONE
Adventure
Comedic
Dark/Grim
Drama
Dystopian 
Epic
Experimental, incl abstract
Light/Positive
Mystery
Survival
Tragedy

== UNIVERSE -- aka originality
AltHistory
Anime/Manga
Inspired
Original
PreExisting

And here are some I don't understand:

- Psychological?
- WorldBuilding? I see this a lot but I'm not quite sure what it means
as a tag. Does is mean the participants are going to  all develop the
world together?