I can strongly relate to many of the positive aspects, that were mentioned before: this game is a great experience! What I´d like to add:
One of the things, that make this game outstanding, is it´s ability to get your imagination rolling. This applies to the characters, the story and the world itself. For example, there is enough stereotype and setup to fill in what is not shown or explained and yet so many unique ideas to be constantly curious, to get invested and interested.
The intro, for example, works so well, because we have seen similar situations before and can instantly jump into the action without much exposure. But already in the next scene, we are introduced to a situation, which is not as easily assessed, where some borderline evil mutants, who are “friends” of yours, are about to eat an Elf! Do I go against them, give up the girl or do I give up something possibly very valuable to rescue her. Here I am, not even 5min into the game and confronted with a choice, that feels quite consequential.
Also, the MC is very varied in his relationships, because he combines different roles in a somewhat believable way: father, mentor, husband, seducer, master, subject, conqueror, breeding material. So every girl/sex-interest is not only defined by the girls character, but also very strongly by the type of relationship. This is nothing new on its own, but I have rarely experienced it in such a varied way.
Lastly, I find it a HUGE benefit in a harem game, that you are already married. No more “It´s ok for me if you love us all”- lines ;-)