This game novel flopped for me for two big reasons.
First reason, I dislike three characters out of four, and the forth one, I don't care about. APBLU offered me a little epiphany about what I don't like about these setups. In essence, it's a violation of "show, don't tell" rule. The story tells me that Laura and Harry are a couple, yadda yadda. And I don't buy it, I just can't. If I don't get to see the story how their romance grew, I fail to see the chemistry between them and care about the relationship that's going to be ruined in this story. On top of that I really did not like the introductory scene. So I don't like brain-dead protag Harry, Aya is a little annoying shit, Luca is a stereotypical shit, and Laura is meh at best. Eight Deadly Words (I don't care what happens to these people) apply here pretty well.
Second reason, the game offers me extremely little choice, and only when the situation is way beyond salvaging (and the very first choice has the second answer disabled because it's not implemented yet, another slap in the face). It really knocks any impact out of the choices. Yeah, I get that's what unavoidable in unavoidable NTR stands for. Well, I don't like unavoidable things in games. Why would you want lack of interactivity in an interactive medium?
Oh, and about those Rules that everyone's talking about. It's not a mechanic, it's a story element. Difference being, a mechanic is something a player controls or directly interacts with (spoiler alert, these rules are exactly not that). It's a fun —but hardly unique in dom-sub setups— story element, and its almost sole function is to drive the logic, flow, and sometimes kinks of porn scenes. On the flipside Laura is absolutely dogshit at using rules to her advantage which means what? She's either dumb, or is not really trying to win; either way, this makes it really hard to care about her.
On the technical side of things, the game is nicely animated and directed (by which I mean the use of camera movements, transitions, and character sprite movements). Unfortunately, art quality is quite inconsistent. Some of the commissioned artists are good, and some don't know the basics of human anatomy (watch some porn, for the reference ffs). Worse, sometimes art doesn't match the text. Which is especially egregious when it doesn't match the rules gimmick. So you've just introduced a rule about raising arms on demand —and even had a long fierce argument to underscore its importance— and then you show a CG with arms not raised? Come on.
TL;DR. Art quality is inconsistent. I failed to like and therefore sympathize with most characters of this story. The "mystery" POV has very little porn and doesn't offer enough choices to make it worth. The "omniscient" POV has decent porn, but offers no extra choices while probably tripling word count, and therefore feels almost like a kinetic novel. Let me watch this from Laura-centric perspective, and you have a chance to get 3 stars, a rating I normally give to a good kinetic novel.