I too appreciate that this game is not diluted by a bunch of random girls to inflate the content and drag the development. If a side character isn't pushing the incest content further, it shouldn't be included.I saw that this had a new update. I called in sick from work and played all the new content. I came five times.
What makes this game so good:
1. The incest is explicit. That is, the characters outright state that what they're doing is incest.
2. The incest is taken seriously. That is, the characters aren't (always) casual about the incest that's commited.
3. The incest is the main focus. That is, there aren't a boatload of non-family chicks to bang, which would turn the MC into simply a horndog not bothered by incest.
4. The tabooness of the incest is stated as being a turn-on for the characters.
5. There's a specific goal that the MC is motivated by. He's not just trying to bed some chicks; he wants to be the man of the house.
What keeps this game from being perfect:
1. I've reached the end of the content.
The five main girls are already straining the creators.