is the game purely dad/daughter incest or there is more?
In the first game (S1), it's basically only the dad and the daughter. In the second game there are other options as well, but the story still mainly focuses on the dad and the daughter.
When I started playing it, I had no expectations and fully planned to fast-forward through it. Mostly because the premise reads as if the game has no depth at all and the game only has 2 characters. But, for some reason the story grew on me and, especially in S1, both the story and the character development of the dad and the daughter are surprisingly good. A bit weird, but still pretty good.