To expand on that last point, let's say you were to use above obscure text command, that you can only find by unearthing a forum thread from 2017 or being told directly, to filter out horror games: https://itch.io/games?exclude=tg.horror
That works for that one tag (if you happen to know this command), but what if you want to filter out multiple tags??? Maybe I want games that are not horror and also not pixel art, or visual novels or who knows what... Do you add a comma? Does it even support more than one tag at all? This is a pretty clear example where there really needs to be an interface for this so you can easily combine different filters, positive or negative, to get the results you want.
Perhaps look at Random Bundle Game for inspiration: https://randombundlegame.com/