I'm surprised I haven't seen anyone mention it yet, but your "direction" is absolutely incredible. The camera angles are all very purposeful and significant, I'm having a hard time pinpointing some examples because I would be here describing almost every single shot in the game lol. Probably my favorites are the zoom into the women's eyes to indicate their desire for the MC (escpecially his subtle reflection in his neighbor's eye), and the close-up of Rose's hand and her clench as they hug. Just beautiful work. A lot of these games feel very washed out and it's just something I've learned to tolerate, but the lighting in this game is superb. There are a lot of games with the MC as a photographer getting into shooting models, which can get a little repetitive, but I think it's really the best way to naturally get a lot of good poses in the game and show off the character models as much as possible so no complaints from me.
The dialogue isn't perfect, but it mostly feels very natural and I like the sister relationship. A lot of people just slap the incest in to add a bit of excitement and it just feels like casual sex with no love. Here you can really feel a deep familial bond between the two to start with, which is perfect. There is a possessiveness (Kat thinking all MC's exes weren't good enough for him) but no outright jealousy (teasing aside, she seemed mostly okay with his attraction to the neighbor) and that made it feel more like a real sibling relationship. Definitely more skinship and nudity between the two than normal, but it is a porn game after all lol.
One small complaint I do have is at the beginning when you're setting the relationships the first one has you replace the word 'roommate' with 'sister', simple enough, but then the prompt for Rose says "dad's twin best friend" so I thought I was just replacing the false relationship with one that makes sense, in this case it was "dad's twin sister". So I put 'sister,' thinking that would automatically make her relationship 'aunt' because it says his dad's sister, unfortunately it made the relationship 'sister'. So maybe somehow you could make it a bit more clear that you need to put 'aunt' for that one?
Another thing I love is the inclusion of these instrumental music covers. Anytime, anywhere, Heart Shaped Box always gets me emotional. =) However, I'm worried you'll get in trouble for using these copyrighted songs, even though they are covers. Be very careful. If nothing else, you can replace them with more generic BGMs for the patreon version and make an "unofficial" patch to put them back in and post it here, or "leak" it and have someone else post it so your hands are technically clean.
As for future tags, everything looks great, although personally my top fetish (the opposite of a fetish really) is impregnation. It's literally the sole purpose of sex, after all. Mixing your genes with the ones you care about most, creating a child that is the physical manifestation of your love for each other. Pregnant sex scenes are nice, but that's not really what it's about for me, it's mainly the results. There are too many games that have the impregnation/pregnancy, but don't have follow-up. Summertime Saga has various stages of pregnancy, as well as the mothers holding their babies and a daycare for them. Corrupted Kingdoms even magically ages your children to around 4 years old and there are heartwarming scenes where you just spend time playing with them and their mothers. That's what it's all about man. Even just a quick scene at the end with the child is nice, like the end of Lust Epidemic.
Anyway, even if you decide not to do pregnancy, your game has some of the most potential I've ever seen and once I've got a steady paycheck again I'm becoming a Patron of yours. And I can count the number of creators I've subscribed to on one hand, so trust me when I say that means something. Good luck and I hope you get the recognition you deserve!