Is there any kind of plot, or is it just a sandbox?
The good part of this game is gonna be the sandbox. I wouldn't expect a plot with multiple paths to tell you the truth or something like that.
This game is a gem on the sandbox part, it just needs more content and more polished. We are talking about npc's that have their own fetishes and dislikes, slavery, companions...
Of course nothing beats a good unique NPC, but that's because they usually have an unique personality. In fact for now NPC's that's what they need, personality archetypes. That and remembering things and acting upon that. At that point... it should be a great game.
The highest level would be Npc x Npc interactions, like falling in love with each other and things like that. Even more would like to see jealous NPC's.
Personally I find that this game represents quite well something optimal in my opinnion. It just needs more development, but this game... it's on my list of special games, and there are very few games there.
P.D: The only system that currently I find it very meh is currently the fetishes levels. I think that it should be something more... "dangerous" to level up, in the sense that for example if the MC or a NPC has a foot fetish, how strong it is should have an influence, perhaps you would be distracted in combat, or perhaps a NPC will treat you as their foot slave, same with other things like cocks, milk... too much of something isn't good.
I think that characters should have it easy to get to level 1 of all fetishes, but falling too much into your fetishes (basically doing it a lot without letting time to pass between each time you fall into your desires) should level it up.