I think they could work out as long as they don't focus too much on sex. If you want a game to be scary then you kind of can't make it too horny. It needs to feel tense.
If it's like goofy scary like a FNaF game it's fine, but if the game is actually spooky that's too different a gear shift for me. I don't have those particular wires crossed.
I can't take horror seriously. Whether it's in movies, whether it's in literature. The same goes for games. But on the other hand, it's a good sleeping pill.
It's kind of a.. complicated fusion to make, isn't it? Like.. In horror, the punishment for failure is being scared, but in a lot of porn games, the 'punishment' for failure is the lewd route (in terms of like loss scenes in RPG games) or NTR or something, so I feel like a fusion of the two can only really ever be a parody because of how divorced the two are.
Otherwise you end up with a whole 'Oh no, I hope the evil demons don't eat my ass' sort of scenario and I feel that undermines the horror.
That said, things like body horror and gore exist but that's not really.. horror, that's just.. someone else's thing.
It's something I enjoy. Horror, gore and so on. Not everywhere, not at all times but aren't we all looking for some fantasy in games? Sometimes weird fantasies - like in movies? I can only speak for myself but believe we all do.