If famed movie director Uwe Boll ever made an adult VN 23 Sisters would probably be it.
The "story" is completely demented. It's about some guy whose father is a super genius billionaire who basically controls the entire world and even rules over some galactic federation. Said father is seemingly dying and on his death bed he meets his son and tells him he will inherit 12 billion dollars if the son (the MC) impregnates all 23 of his sisters. As it is the father has a huge incest and breeding fetish, but you probably already guessed that. And of course the MC agrees to the deal.
What follows is over the top wacky nonsense about impregnating all the sisters, plus unofficial sisters and a few other females along the way. The MC gathers all the sisters he encounters in a huge apartment building owned by his father who, after he dies, uploads his mind into some kind of android.
The girls in the story are not just humans, there are also angels, demons, (half) aliens, goat girls, cat girls, moth girls... and most of them look very underage....
Oh, since the MC's father is a genius he developed several drugs that make the MC irresistable to women who have a commonality with him (like a sister, for example), another drug makes sure the MC will impregnate any woman at basically the first try, and almost all the potential sisters were put on special fertility drugs (without their knowledge), these drugs also accelerate the pregnancy so it only lasts about two weeks, with each subsequent pregnancy developing even faster. And the drugs also make sure that all the children will always be girls so the MC can then go on and impregnate them as well.
The demon character gives birth two hours after impregnation btw. and her child is more or less grown up shortly after. Yup!
So of course the newborn daughters all have accelerated growth and are mature after a week or so (the demon girl is special) and yes, all of them want to be bred by the MC right out of the gate.
And yes, all of them live in one gigantic harem and all of them always walk around in the nude while at home, because the MCs "alpha" sister Tiffany wants it like that. And yes, Tiffany also has a huge incest fetish. But basically everyone in the harem has one. But Tiffany takes the cake. And yes, she's from Alabama. Ha ha...
The sheer madness is actually kind of impressive. Some of the over the top writing is even outright funny. There are a few laugh out loud moments in the game.
However, ultimately 23 Sisters suffers from mediocre renders, various not very attractive female characters and making so many of them look very underage (not my cup of tea at all).
Also, for the fact that 23 Sisters wants to be an over the top porn parody the sex scenes are just horrendous. The animations are short, very, very slowly paced (the movement is ultra slow) and there is zero variation in a scene.
Also, since there are so many sisters plus offspring you quickly forget who is supposed to be who, not that it matters, since almost all female characters only serve one purpose anyway and it really doesn't matter what girl is featured in any of the horrendous animations.
To be honest, I cannot recommend 23 Sisters to anyone who wants a VN to be at least somewhat plausible or expects decent production values.
If you like over the top wacky comedy and if you are ok with characters that are paper thin, and always wanted to have a game that goes to town with pregnancy and incest content then 23 Sisters is certainly enjoyable. However, the lousy adult scenes in this game are a major shortcoming. There is also surpringly little interaction between the various sisters / daughters / whatevers with or without the MC, there is some, but not nearly as much as someone may expect, given the ridiculous setting.
But if you like crass and silly humor and don't care about lousy animations, lousy characters, female DAZ models that look disturbingly young, and if your tolerance threshold for sheer madness is rather high then 23 Sisters can certainly be fun.
The jokes can be pretty good at times, but the interactions with the female characters are usually super boring, you will care for almost no one in this VN and there simply are too many characters that you completely lose track of after a short while because the game keeps throwing new characters at you like candy. And the MC has only met about 1/2 or so of his sisters so far with release 0.10.