https://www.dlsite.com/maniax/work/=/product_id/RJ420932.html

It seems like a family hentai
Son fucks his mother, his sister and is sister livign alone or cousin
but then is shown that his father does the same
is a game so I don't understand if who fucks who depends on som echoices or no matter what the son starts and the father follows
I can't even say if is NTR or sex sharing

Base +10, ScrawnyJohny +6

Blond is a younger sister/daughter. The girl with teal hair color is an older sister/daughter who's living separately but decided to visit them.
The game is super easy to navigate as you just switch a lever on the left for a male and then on the right for a female (to select the older sister/daughter you need to switch mother's lever several times) and scenes follow each other in an anthology format. Every pairing has several scenes so you need to select them several times to watch everything (mother/son 5 scenes, father/younger daughter 3 scenes, father/older daughter 5 scenes, brother/younger sister 3 scenes, brother/older sister 2 scenes). There's no father/mother scenes since it's exclusively incest game.
Also no ntr unless you count mother/son as cheating but father knows about their relationship and acknowledges them.

Base +11, ScrawnyJohny +6, Allcush +1