In terms of the incest fetish being popular, there's a few things I know that makes it good:
- It breaks taboos, possibly the most universal taboo in human history.
- It involves age gaps (unless sibling incest), which is a bit of a fetish in itself.
- It often involves corruption, which also is a fetish in itself, OR
- it can involve romance/intimacy, etc. which is nice, and leads to the next point:
- It has the partners in an already involved relationship, and know each other well, so you can skip the "getting to know each other" phase of writing, which is often tedious and a bit boring/rote.
- Lastly, I mean, the Oedipus complex has been around forever (Freud interpreted is as the drive for young men to want to prove themselves by getting the sexual approval of the most important woman in their life, ie. their mom. The same goes for girls, though that's called the Elektra complex. Basically, there's a tendency for people to mentally model their ideal partner on the parent of their opposite-gendered parent, and in the cases of these complexes, something happens where it transforms into literal lust for that parent.)
- Like most fetishes it involves living out a fantasy in a fictional setting as opposed to actually want it in real life (like with rape fantasies or whatever).
I realize this a "light hearted" game, very colorful and all.
Has dark cookie said anything about "rough" or "hardcore".
Like meeting a new character and she wants to try a little choking?
Not that I know of planned ahead - however, there already a bondage/domination scene with the nun and a classmate's mom in the game, and some semi-dom stuff with that woman.
Although, given the way the MC is written, like a mostly hapless teenager kinda just having a good time with stuff and taking things as they come, he really wouldn't fit in a hardcore bdsm scene thing. Maybe if the girl asked him to choke her, but that's about it. He's a pretty chill dude (some would say milquetoast, but I like him, he seems more sympathetic than a lot of h-game protagonists).