This is one of the few games using RPGM properly, as intended, explore, fight, learn, become better and claim your reward. It's an actual role playing adventure game with porn content. As others stated, you can feel your progression and with each step getting immersed even more.
I dislike and try to avoid VNs pretending to be a game using RPGM engine, big map but empty world, railroaded content giving false hope of exploration and sandbox, etc. But I don't hate RPGM engine, because if you use this engine as intended then the result is charming, fun, addictive, immersive as we can see in Tinkerer's work.
For anybody saying that this game should be converted into Ren'Py; you guys/gals are probably not looking for a game, but actually looking for a VN or a comic or a picture book. But if you're in the minority and only prefer RPG with Ren'Py, sure there are good RPG games made using Ren'Py, but those have very different tastes and experiences.
I played many good games with lots of different engines, Unity, HTML, QSP, RAGS, Java, Flash etc. And almost every engine adds a different taste to games, sure some are very similar, but some are also very unique, more immersive. If the dev has the skills and can use the engine good, then try to enjoy those games as they are if you can.