Twisted, is there a guide or something that you could recommend on how to make a RPG/VN like this?
The only guide I could give you would require you to be an established professional artist first. An aesthetic or art that draws people in will be everything since you're probably not going to be able to make the next "Corruption of Champions" any time soon. I suppose you could use 3D models instead, but it's such a saturated market.
If art sells the game, writing makes it stand out and get good reviews. Without good writing, your game probably isn't worth playing compared to literally browsing porn on the web.
Writing comes naturally to me, but I have read several books on how to write stories, watched several writing lecture courses, and played or studied a variety of popular and well-written stories.
Sound design is also important to me. Another name for "visual novels" is "sound novels," and your music and sound effects should not be an afterthought. Sex scenes should have good music, good moans, and good sex noises. I can't get all three in the limited RPGMaker engine, but my future games will include them.
Some kinetic motion for the sex scenes and gameplay in general is also important, and I don't just mean animation; movement in general makes a big difference, and there will be clever ways to implement this into the game, such as swapping between 2-3 frames using a dissolve transition to make it look smoother than it is or utilizing parallaxes to give scenes more depth. Again, I can't do this in RPGMaker, but Ren'Py is the perfect engine for VN-based game design and I can't wait to get back to it.
In regards to game coding, mechanics, development, and knowing what works, you need to get experience, but watching tons of game analysis and video essays on YouTube helps. In the process of designing Monster Girl 1,000, I've learned absolutely tons about how to better design menus, guide the player, and implement various quality-of-life features that never occurred to me at first.
