I presume this is about sexuality. Plenty of adult games that are just mature rated because it glorifies violence (like, y'know...your average GTA game). Though admitted, some are blurring the lines a bit...
Post void is...something. It's a roguelike shooter that's I presume is like playing wolfenstein 3D on acid. The perspective is weird, you're constantly running out of health (meaning: you only survive by sprinting and headshotting everything) and...well, the aesthetics speak for themselves if you look it up on steam. Though you've got barely time to even glance enemies, some are downright pornographic in nature (I remember some sort of barrier/enemy that's a woman with open legs you've got to fire into to pass through).
Song of Saya is barely a visual novel, let alone a video game. It has maybe a dozen images, the rest is text and a few sound bites and eerie music. And maybe a handful of choices that progress the story in a certain direction. But man, is that a punch to the gut. Your character is a survivor of a car crash in which your parents died. The wound strangely affects your perception of reality that makes the world look and smell like a rotten abattoir. As such, you feel disconnected (even more) from your friends and are on a mental downward spiral. That is until you meet Saya, who mysteriously looks like a normal girl to you.
(however: unbeknownst to you, Saya is actually some sort of Lovecraftian spawn that hides from the world).
It's...I guess a sort of occult love story, though some parts gets explicitly graphical (and yes, these are imaged...think tentacle rape).
Doki doki literature club. This free game is...I guess a spoof or dark parody on dating games?
(I never play those) It's decent, but I admit it's a "one time playthrough" thing. As an actual adult (I'm 40+), the atmosphere is kind of timid (read: you play as a teenage virgin). It gets twisted in an unusual way, though.
Not sure I should mention hunie pop. It's an okay match-3 game. The thing is: the theme doesn't add anything. I guess the same goes for sex chess (not tried that one), but ey...you do you.
Last but not least: Lula, the sexy empire. This is an oldie (it's on GoG). It's a point'n click game from before the standards were set. You play as a pimp who meets Lula and goes on to build a porn empire. It's kind of crude and comical (think Leisure suit Larry), but underneath the cheap pictures and crass humor is an actually decent tycoon game. Or rather: three or four tycoon games. I don't remember it being an exactly hard game, but the makers genuinely wanted to do more than just throw out a forgettable game.
(edit: maybe I should mention "the static speaks my name", though it's not about sexuality. It's a small and free walking simulator of a depressed person who wanders through his appartement. It was only like 15 minutes long and I played it years ago, but it haunted me FAR more than anything that dares call itself a horror game).
