Was probably a waste of my time, I'm not into NTR, but the plot is actually a kind of vaguely interesting set up? But the game doesn't really do much with it at all. It's weird though, because near the end of it (during the prison), they clearly thought up a kind of like world setting and stuff. But there's not much that's really done with it.
The route ends all establish the idea that they need to 'gradually' weaken the protagonist's heart then shatter it, but funnily enough, all those endings are actually pretty good outcomes for the worlds at large - because his heart doesn't actually break, so the plot to merge the two worlds never happens. It means a bad ending for the protagonists in general, but ultimately for the world and all, actually a pretty high note.
Going for the Normal End actually means the evil plan succeeds and it's bad for EVERYONE involved (except the villains, of course). And it also contradicts the idea of the gradual breaking, because his heart instantly breaks upon that single scene regardless of the Mental State.
Speaking of the Mental State, it doesn't actually seem possible to hit 0, since even after seeing all 4 routes to the end, it'll still have a bit of the gauge full. Unless there's some secret bad ending if you use a save from THAT to then go into the normal end? I didn't try. Not sure I care enough to, honestly.
The Happy Ending though is... alright, honestly? But maybe because I actually like it playing with basically subverting everything bad that happens, and the plan is foiled, and everyone gets a kind of happy ending. It's a bit bittersweet regardless, because either Rinka or Mitsuki will end up not getting what they want in the end. And there is, oddly, no like third option to just have them both. Not unless you have to see the two endings, then maybe a third option appears, but again, not sure I'm really too keen to try. Not that it takes too long to test, I suppose.
The battle system is entirely pointless really, but I can at least appreciate that they avoided making it completely annoying. It's super simple and (fairly) fast, so you can get through it quickly. But as mentioned, it's also pointless because there are no boss fights. This kind of plays into a positive though, honestly, because they could've easily just made this game a huge slog with them. But it could've been nice to actually let Rinka/Mitsuki actually get to fight Takane and defeat her, and change some things. But I guess the dev just wanted a pretty linear experience without any real branching.
Speaking of branching... that's another big weakness of the overall game when you get into it. The individual routes have no actual impact on Rinka's side of thing, beyond changing her H stats. But otherwise, there is no actual impact on that story at all. While it makes for an easier game experience I guess, it also makes it feel really tacked on.
And on the H side of things, I'd say its fairly standard. The art is nice, and the girls are nice. but the actual scenes I'd say are pretty miss, but that's mainly because every guy involved is always the super ugly type. It's something weird to say when the Goblin is probably the most NORMAL looking one involved honestly. And he's even the NICEST of them all ultimately, being actually unaware of who Rinka and the protagonist are to one another until his ending. But this could be a translation thing.
Speaking of translation... also kind of hit or miss. I think its ultimately kind of right, but it messes up s/he things from time to time. Mostly with the male protagonist side, where he's sometimes a she for no reason, or called a girl. Which actually had me think that could've been a great twist, if somehow he was actually a girl or something in the end. Not sure how much it'd change in the end, but I'd find it funny if an inconsistent MTL actually turned out to be foreshadowing something like that.
So ultimate in the end, I'd say it's solidly "eh". I'm not sure what NTR fans look for in a game, and I'm not sure this is it. If you really want to, it's a really fast game to finish though, especially as you can skip the Rinka side of things on the NTR routes, which greatly speeds up that process. Only took me around 3 hours, and that was just reading the parts I figured are actually about the plot. Maybe left the game open a little bit, so maybe it's more like 2 and a half, or less. You can just skip every goblin fight, since the combat is pointless.