First, I have just downloaded the game, but haven't played yet. So keep that in mind.
Second, regarding incest. Yes, there is a large (no idea how many, it's just my echo chamber) group of us who want that content. Yes, there are a lot of games that have a patch, with varying degrees of success. If you include a patch and implement it well, you'll retain that large group. Some games have done it extremely poorly and I have stopped playing games because of it. I see you have a Subscribestar link, so you shouldn't have any issues keeping it w/ the incest. Changing it and making a patch will add additional work (not sure how much, since I haven't made a game), but it's YOUR GAME. Always keep that in mind. You will never please everyone.
Suggestions? If you want to lean in the blackmail genre, do not allow the girls to display excited facial expressions (at least not too soon).While NPC games with expressionless faces are popular and the majority of games offer a sleepsex feature, expressionless sex is somewhat uncommon on this site, so make use of that. I would choose a procedure similar to this: Anger, quiet sobbing, sex without expression, reluctant and/or irritated cooperation, and ultimately turning them into sex addicts.
YES! This is awesome! This is the way!
Then throw in some optional(!) bdsm, choking, pissing, and not unimportant; sharing, and you are golden. These are not just my preferences, look at the most populair games like Desert stalker, Power Vacuum and Pale Carnations.
As Antoon says, OPTIONAL. That will keep a lot of people happy. Pissing isn't my kink, but if it's simple, I won't skip the scene, if it gets more... graphic/intense, I'll skip. Always have the option for these things (played another game which added some bdsm (not optional) and people quit playing over it.)
People go completely balistic about NTR, so stay away from it at all costs. And be clear about not having it your game, unless, of course, you want an NTR-focused game. Do not try to please both sides; it won't work very well on this site.
This is true. I do not like NTR and avoid it, but I have played a lot of games that had NTR routes and sometimes for completion sake, I've played some of those routes, but not a fan. If you add NTR, make it OPTIONAL. And make it very clear that it is totally optional. I swear NTR is the biggest trigger (for both sides) on this site.
Oh, and keep the grind to an absolute minimum, or better none. If there has to be grind, keep it relevant to the story; the fewer clicks, the better. NO MINI-GAMES!!!
Most people seem to dislike mini-games. I like them, but they need to be relevant. If it's cash earning, add an option to "skip the mini-game" but you get the same rewards as your last played (so you can choose to try and improve how much you get.) Also, you can add a passive way of earning money, by say taking pictures of the LI and uploading them to a page. The more pics you upload the more money you make... so over time, you can skip the other mini-games all together. Having a mini-game where you have to scale a fence, climb a ladder, then sneak open a window EVERYTIME you go to see a LI, is a terrible idea! If that dev had you do it once time and that was it, it would have been fine. But it was every time.
Anyways, I hope these inputs help. Good luck with your development and I look forward to playing your game!