TL DR: Intriguing, but flawed.
Even though not entirely novel, the concept of mixing cthulhu and adult entertainment is pretty rare, making the game immediately stand out a bit.
A few things, RuinMe does exceptionally well.
For example, I really liked the writing in general - having never read Lovecraft myself, I still could recognize the theme very well.
It's "in character", often using "vintage" terminologies, depicting social classes, the sexes or different ethnics in ways that are now a thing of the past. The mixing and/or use of otherworldly presences for adult entertainment is generally very well done and "believable".
Generally a, maybe THE, strong suit of the game.
The trainer aspect of the game (considering the title, it shouldn't be much of a spoiler to reveal it's mostly centered around bdsm) also is very well done, in my opinion. Not always perfect, but close enough, the escalation of "challenges" is reasonable and most of the individual scenarios are ... inspiring, provided you are open to the respective kink even a little bit.
There are usually choices to make the scenario play out less or more harsh, depending on your preferences.
Maybe the heroine is a little bit too forthcoming, but again, given the title, that should probably not be a surprise.
Another strong suit of the game.
Unfortunately, I think that's about it for the net positives.
So-so are the backgrounds, which are filtered photos which fit the scenes quite well most of the time, but (with a few exceptions) don't do a good job of supporting / enhancing the storytelling.
Also the grind, which is there, but extremely mild. Basically, there's only a single option you might want to use a couple of times, and even that can be avoided if you just skip days, as the game isn't really on a timer.
Which brings us to the negatives.
Most prominently, that's the ms paint level character portraits. As bad as they are, 90% of the time, the game choses to not depict things at all. The writing manages to get the point across, like I explained above, but is it still a "visual" novel if almost nothing is actually depicted? I was definitely disappointed.
Next is the open world. It's quite well realized, I don't think I ran into a single coding error and sometimes the game makes "clever" use of it, but in the bottom line, I really have to question it's purpose.
Sometimes you will have several quests at once which you can choose to pursue, but either they are not really side quests at all but connected to the main plot or they are totally nonconsequential, serving just as a vessel to depict a certain idea/scenario the author had in mind. There's not nearly enough of those to make "navigating" the world interesting or even intriguing, it's usually crystal clear where you have to go next in a quest, and once you "cleared" a location it usually becomes pointless to ever visit it again. Thus, in the bottom line, the purpose of the open world is to annoy the player by having him perform a series of pointless clicks.
Finally, I have to mention the characters. Some have are at least a little bit defined, but not a single one feels fleshed out, not even the player character of female protagonist. Like the graphics, the characters also have a ms paint level quality to them, if you catch my drift.
To sum things up, I didn't regret my time with the game, but in order to be a good game, it needs massive improvements, imo. More things depicted - even if it's in ms paint, preferably the graphics should be a tad better, though.
There should be meaningful choices. Do I play as a male or a female? How do I deal / get along with the characters in the world? Was I a harsh master or mistress or was I benevolent in my training? Did I fight the incursion or did I succumbt to it willingly? Decisions such as these should offer the game replayability, and they currently do not.
There should be more to the world in general (more events, more quests) and, combined to the effects of choices mentioned before, this would give the open world a purpose and raise the game to a whole other level.
As it stands, though, the game's a novelty. Worth playing especially for the in-character writing if you care at all about Lovecraft-style worldbuilding, but pretty forgettable otherwise. Also, not really "fappable", which might have relevance on this site.