The title pretty much says all you need to know. This is a harem game where you seduce and fuck your three sisters, and your mother (and numerous side characters), all at once.
Is the game realistic? Not at all.
If you want the "plot" to be sensible, probably you shouldn't play an incest based harem game.
With that out of the way, if you accept the ludicrous premise of the game, it is great.
In this game, all the women are beautiful, and virtually all of them, even family members, will throw themselves at you after just two or three acts of kindness, and maybe one or two acts of "corruption" like perving on them to get the ball rolling. After that they will happily form a loving relationship with you even if they have to share you with others, and you can all fuck happily ever after.
It is a pleasant fantasy, that we have undone thousands of years of cultural conditioning and reverted to Bonobos with our sexual habits. But if it all sounds too creepy or too unlikely, you will not enjoy this game.
But just having lots of sex with beautiful people wouldn't really stand out in the adult visual novel genre. Though the sex is not animated and not extremely well rendered, it is quite nice, and there is quite a degree of variety and a number of kinks catered for. There are a number of body types catered to, though as seems usual for this field, every girl seems to have the same shaved, little innie pussy.
You can actually just not creep on your family and help them without "reward" and date some of the side characters, if you want. There is enough variety and player agency to allow quite a few different scenarios and reward several playthroughs, though each will tend towards a similar plot line.
Apart from the great variety and many meaningful choices, the really nice part of this game is the characterisation. All the love interest characters are relatable and sweet in some way, and talking to them is genuinely nice. The drama moments with them feel impactful, and the happy moments feel rewarding.
I personally really loved the three sisters, and particularly Bella. I was actually smiling during every date with her on the romantic path (her giggle on your first awkward non date is delightful), and the dom/sub path was hot as hell. I loved the bowling and burger date (and the different ways it plays out). Actually, I quite liked the domination of Bella at the Pizza scene, and the dinner date with her. Maybe I have a public eating sex fetish...
All given the premise, of course. If you can't get over the premise none of the characterisation will mean much, and will seem as unrealistic as it is.
The plot, as it is, revolves around the idea that the characters know incest must be hidden, and they do their best to grow their relationships within this constraint, until they find a solution.
Each main character has their own plot as well, and these are more interesting than the main plot, which really just serves as a timer to allow the game to wrap up once everyone is happy with each other (or unhappy as the case may be).
Maybe not actually having any sisters helps me to ignore the silly fantasy parts of this and just enjoy dating several lovely people at once.
TLDR: Within the fantasy of an incest based harem, the plot is well done, especially the character arcs. The characters are sweet and growing your love for them is satisfying. The sex is not animated, but pretty enough and quite varied. If you just want lots of sex scenes, this is good enough. If you want them with some lovely characters, this is outstanding. If you want it to be realistic, this is not for you.