Well, the answer to the above question is simple... I saw the monster girl anime for this season's first episode and got curious about what kind of content these games had... to be honest, I was planning to drop it inside the first few hours, using it as a break from more serious content before starting Baldr Force.. but I was surprised to find just how good the writing in these games is.
That said, the early games (the Lamia and Alraune games) are nukige, as presented... and the H scenes are kind of guro in a lot of cases (to be honest, I can't get into the H in this series at all, lol). However, I was kind of stunned at how good the writing is in the ones I've played and how they created a sense of connection and continuity between all the VNs in the series. First, you have to understand that all the VNs prior to Monmusu Gakuen are written in the same general period of the setting's history and Gakuen is written in a period fifteen to twenty-five years after those (the kids from three of the VNs are heroines in Gakuen).
The most solid of the VNs as a whole is the Arachne/Harpy/Cyclops VN, which focuses on Hibiki, a guy who basically gets summoned from Earth by Ariane the Arachne on a whim... The speed with which he adjusts to his new lifestyle is a bit unreal, but the interactions between him and the heroines are endlessly amusing... and the actual story of each path is touching enough emotionally that I cried, despite the fact that I had to skip past the H to keep from being ill in some cases (you can tell that the writer is basically acting out his fetishes with enthusiasm...).
The Scylla/slime VN is the second most solid, with a somewhat... free-spirited pirate as a protagonist. The slime is a total moron who believes anything the scylla maid says... which wouldn't be so bad if the scylla's hobby wasn't making her look like an idiot. I spent most of this one just laughing... endlessly laughing. I laughed until my jaw hurt with this one. The general absurdity of the VN's premise doesn't in any way take away from the comedic character dynamic or the emotionality of the heroine paths (there is pretty much nothing emotional until you actually get on those two paths).
Monmusu Gakuen is the weakest of the three I completed (three VNs in two days) and it retains a lot of the atmosphere of the other two... but in exchange, the H is even more guro and the number of heroines kind of dilutes the emotionality of the paths in several cases. Nonetheless, it is easy to get attached to them, simply because of the protagonist's point of view as their teacher.
I came out of curiosity and stayed for the writing.
I'm just curious... why is it that some of the best VN writers are the weirdest kind of pervert?
Edit: I almost didn't write anything on these... but I felt I owed it to the people who might actually be interested in this kind of interracial romance story to at least say something about my experience. I just also felt the need to warn you that... if you have imaginings about the H, it is actually probably a bit worse than you imagined.