There was some kind of saying I heard some years ago. If you read good American English somewhere, a European wrote it ;-)
There even is a famous song, Tainted Love. Ok, the better known cover version is from 2001, but it is used about every year as a sample in another song. If you would ask me, "tainted" and "love" are commonly known by association for that song and its dozens of cover versions alone. Even and especially in North America, as Marilyn Manson is American.
Maybe Tainted Lovers would be a recogniseable title ;-b . Along with the word play, that they are presumably tainted by Lilith in another way as well.
That list was just to verify if fantasy or rather non drama is mainstream. Yes, people do like to watch nieche entertainment on streaming. And GoT was even a driving factor to get subscribers. But that is exactly the point. It is so nieche, that you do not find it in mainstream and have to go to streaming. Same for vn. Either it is anime style or slice of life. Other kinds are rare in comparison. Ok, my knowledge about vn is a bit limited, because I most often skip, because I look for actual game play (I stuck with yours so far, because of the quality of the naughty screenshots and that girl with the big sword, but this is a singular data point ;-)
You do cover a nieche for porn because of fantasy setting. So you need to play your trump cards so that people looking for that kind of stuff find you and maybe people looking for porn games in general also notice you. If you put Lilith with horns on capsule, from first glance I expect game where I either play as demon or screw demons. If that is a turn off to me, I might not look further. And if it is a turn on, I might be dissapointed, if all the girls in the screenshots are non demons. Those two good selling games put a love interest in the capsule, did they not. And not even with cleavage.
How your demons and or boss demon look is your style choice. Purple and variations of red are more often seen in cartoonish looking settings. Such unnatural skin colors are hard to pull of with real looking human faces, I suspect because of the uncanny valley. Of course it can be done, like some versions of green Hulk or I liked the Orcs in that Warcraft movie. And even Hellboy. But that was fitting in the color scheme used for the movies. There were many vivid colors and much darkness there. Your color scheme is sunny Skyrim judging from the screenshots. Outside of hell fire lava pit, she might look a bit off with that skin tone.
(Your Lilith just does not look like I want to romance her. Maybe hatefuck her, after I reclaimed my country from her dirty clutches. She has that evil stepmom vibes, and I think that is intentional.)
It was fun theory crafting here. I hope you get lots of feedback. But asking the kids what they want for dinner might result in ice cream on pizza.