At first i didn't actually think I would enjoy this, i usually avoid Renpy games (which is ironic because I once made one, a crap one but one nevertheless). That said as i played through this I found myself quite liking it.
The general gist is you are the son in the family of your mother, father and 2 sisters. Your father is a scientist, your mother a biologist, your sister an ex army vet and the other one a pre college student. Complete with the personalities you would expect.
There are 2 routes per character, namely Romance or Corruption. Now what happens is your father is a dispassionate scientist, everything is a lab experiment to him,including you and the family. Unfortunately he can no longer have children for some reason so he asks you to replenish the human population after the nuclear apocalypse. How you may ask? Well...he wants you to bonk! He wants you to bonk you big, ex army sister, he wants you to bonk your innocent naive virgin sister, he even wants you to bonk his wife, your mother!
*Billy Mays Voice* BUT WAIT THERES MORE!!! See there is also a settlement nearby! And a trader that hangs outside your shelter, you can bonk them too!
Said bonking takes place with very high quality renders that are animated (said animation is flicking between two images to give the impression) and the scenes you get differ depending on whether you choose to corrupt or romance the girls.
I played both routes just to see what happens.
Romance - Is exactly that, woo them, slowly and they develop love for you, buy them gifts etc etc. Said Romance cumulates in every girl loving you. Aww....
Corruption - Break em! (this was my first and favourite path), turns out trying to slip 'em the one eyed purple snake firsthand is difficult, so your father being a scientist develops a pill that launches them into a state of sluttiness that not even Caligula could rival! Said corruption results in introducing naive, innocent little sister to becoming a hardcore BDSM Submissive, taking a once proud ex army veteran sister and turning her into a sex soldier who obeys your every command, and turning your mother against your father which eventually results in her being railed behind his back (literally, there is a scene) and eventually in front of him and then the big one, you can choose whether to boot dad out or keep him around as a submissive little maid that does everything around the house while you fuck his now slutified wife and daughters....
Can you tell I like this game? You can see which route I prefer! Do play it.