Hmm.
I have to say that as pornographic video game tags go, the tag library that itch.io provides is kind of limited. The goony.dev people apparently scraped the tags from itch.io's database of tags, which makes sense if their aim is to keep pornographic itch.io games visible. But...if goony.dev aims to be a database of specifically pornographic video games, there's not a lot by way of relevant tag data to make the games searchable.
Contrast with, say, vndb.org's tag library, which has a wide range of tags specifically dedicated to fine-grained classification of sexual content. Vndb.org isn't specifically for pornographic games, but tracks and indexes quite a few, and has a very extensive tag database.
I wonder if it might make sense to (a) link to other vendors, like Steam/Patreon/whatever as well and (b) since there are tags on some other sources, incorporate use of those tags as well to get more metadata, since some games are listed on multiple databases or with multiple vendors. Maybe have a way to ask for tags just from one vendor if there's concern about not forcing users to see mixed data from multiple sources, but that seems like it'd be a significant value-add relative to just searching directly on itch.io or whatnot.