It's nice to be able to filter in genres but I'm not a horror fan and when I'm looking for new games it would be nice to blacklist anything with a horror tag so I can see games without it and better curate my preferences
This suggestion is made with regularity. See this old topic for an answer.
Then. Why has this regularly made suggestion still not been implemented.
That's not a real answer, I made a whole thing about why that old broken "solution" doesn't work: https://itch.io/t/1236107/actual-working-tag-exclusion
The "old" method only works if you are logged into your account. And while vn are a genre, genres are handled like tags. This can seem confusing if you look at urls.
https://itch.io/games/genre-puzzle/genre-visual-novel/tag-horror
That is two genres and one tag. You just strip the "genre-" or "tag-" and add "?exclude=tg.name" and replace name with visual-novel. No " and no / and no . when adding to the url.
You can use that in a bookmark for your favorite search.
The caveat is, that the urladd does not stay, when you change browse options. I made a tool for that, if you are comfortable and able installing browser addons. Works on Chrome. There is also a second tool that can filter by main genre. A main genre is the genre that is desigatned as the main genre. A game can have more than one.
We shall see how or if searchin / browsing might change in the future. Personally, I would welcome an improved recommendation system. Also, I do not filter out game tags, I filter out individual games. Tag filtering is nice on paper, but there are several issues with that, so maybe there are several different reasons, why there is no such feature yet.