The father who constantly says no we can't its not right over and over again gets annoying pretty quickly
I think i now exactly what game you're talking about. A character like that comes of as pathetic and weak. Its like he's the one getting groomed.
I think it would be fun to do something like this in a post-apocalyptic world, a recent apocalipse. The first part of the story would be just 2 characters, the father and the daughter. The mother died during the apocalypse, and the daughter was too young and doesn't really remember the before time. It gives you a reason to explain the backstory and just have them talk and interact as the father tells stories and stuff. It also keeps your set small, cabin in the woods. I think this would work best with an arctic environment, cozy time under blankets and sticking together for warmth, but DAZ and snowy environments are pretty much nonexistent, and heavy clothing is also in short supply and difficult to work with.
As she grows, she starts to look more and more like her mother. Man has needs, stressed out of his mind keeping them alive, and stuff starts to happen. doesn't go too far, but it's clear that it's more than what a man should do with his daughter.
Stuff happens related to whatever apocalipse, and they join up with a large group of survivors. You do this to build up more tension and to add to the fact that they have to keep whatever is happening ilicit. I think this is an important part of the kink.
You have the MC be unsure and guilty because of what he did; he still has most of the old-world morals, and now he has options for women. Did he want her because she reminded him of his wife? Was he just horny and stressed, or does he actually like her as a woman?
The daughter will have good survival skills but be super naive and socially awkward because, yeah, pretty much her whole life she has only spent time with her dad. The only person she knows she trusts absolutely. It will be a good reason to have her lack common sense when it comes to relationships and just people in general while not having her be an actual child or mentally retarded like what most people do.
You introduce more characters; you have the daughter make some friends; maybe she lets slip some of the things she did with her dad because she doesn't even know that those things are weird. You can have some jealousy from the dad because some of the boys are paying a bit too much attention to her, etc.