Mmm Pale Carnation? Have you played it? If not, I should warn you that it's a bit more depraved than other games.
You can also try Wartribe Academy, Oppai Odyssey, Goddess Whim, Phoenixes, Lewd Town Adventures, similar to Pale Carnations but more of a sandbox type.
Harem Hotel, The Headmaster it just doesn't have the harem story and it's not romantic since you are the director of a university, but the plot is very good.
I can also reccomend you 3 longer games and few shorter ones,
Sorry that this message will be so long so if you don't want to read everything you can just look at the names and download it or look up itch page if this games, look up story, photos etc and decide if you want to download it
so if you like more dark climates try NOW AND THEN, it's about zombie apocalypse and from what i heard your decisions are very important (game won't show you that you f up right after choosing one thing and it can have consequences after 2 episodes so pretty long time that is, i didn't completed it yet but i can tell its good)
Another one will be EVERMORE, it's also a little dark sometimes but it's not as much as NOW AND THEN, game is basically about you discovering some power you gained, there are a lot of lore behind basically everything, you have something like book and you can see how something got created for example who is this person, what is this place etc.
unfortunately it's not completed and won't get any update soon because dev have to work full time to take care of everything and he won't be able to update it
Another not dark at first but a lot darker later is SHALE HILL SECRETS game is about you, Shale Hill university student that lost his voice (yes you character can't talk normally) and you can only talk through your phone, there are also a lot disappearances at this school and you somehow get involved in it through some app randomly downloading in your laptop, the further you get in story the more dark things and Secrets you discover about of your school, you need to protect yourself and people you care about
dev just released last episode, 17 of this game, for now game is free till chapter 10, for 11 you have to be patron, and this game ended but not Shale Hill Universe so probably some games will come out one day that are about this university or something like this
now i will list the short ones that i played and i know are good (i will just write name of this game and very short what it's about)
(btw if you played ETERNUM i recommend ONCE IN A LIFETIME, it's from same dev and it have few endings)
So back to the games
TWISTED FATES (having powers, someone is chasing person you protect)
BETWEEN HUMANITY (after road accident you wake up in hospital and some cult is following you (idk for now what exactly it is because it's not full ver for now)
FATES COLLIDE (you go to university, there are some bad things like police working with bad guys for example, some choices are like you can go there or there and depending on it you get different scene for gallery
OUR BRIGHT DAYS (very short for now but it's actually pretty cool game, normal story for now, it is sandbox but it doesn't change a lot of things, good music, animations and you can find qr codes for music for your phone around the map)
CITY DEVIL: RESTART (this is definitely must play, almost everything in this game is animation, even you character running in corridor to get to the window is animated, not that important things, not full game is animated but good part of it and it makes it must play at least for me)
