I know I'm biased since I really like grotesque erotica but even if you take that away from LonaRPG, the whole game and its world actually plays like a sandbox filled with toys instead of your usual H game fare where you're either just hunting for scenes or striking down To Do lists masquerading as quests to get to the next wet bits.
The game is pretty obtuse about how deep it can get and what kind of stories you could lead Lona through or outright save her from. Unlike most other eroge you're not necessarily just going about trying to trigger flags mechanically. The meat of this game for me is how surprising things can turn out for Lona and the game allows for that by doing away with the usual route-based chase and simply letting you discover things on your own; either by accident or on purpose.
I still remember when I fell in love with this game. My Lona was some kind of evil slut and at one point she got caught committing a crime. Any other game this might have been a game over with a scene, but here she got dumped into an actual prison filled with rapists and murderers. That would have been the end for Lona then as the conditions were scarcely survivable and it would have forced me to reload a save. But in this case she was able to persevere and subsist on the other prisoners' flesh after she'd killed them through sex and showered herself in their gore, eventually escaping after some time.
That kind of stuff is the magic in this one.
I adore that part of the game. It is never truly over till Lona dies. There was this one time where I got cocky, since my Lona who was pretty much max level, and I tried to just pass a bandit skill check by just Leaving cause I had decent stats for it. I did so many times... however, this time, I was not so lucky. I used up hide chance, my talk chance, and wasted my last leave chance. One thing to note is that my lona could probably beat 2 bandits in a straight up fight. But when you fail to hide and get into a fight with bandits in the tight corridors of Noer, there is no escape and you end up having to fight at least 4 to 5 bandits that are well equipped. This was indeed my fault as I didn't respect the threat of bandits, especially in Noer setting, and I didn't play it safe. I knew straight up that I would die if I fought back, this was a doom play through so death is permeant, so I quickly spammed menu button just praying that I would open it before they engage combat with me. Thankfully, I managed to open menu and I stripped out of all my gear, putting them in my inventory, and put the "KKAAYYYAH" action (the one that insta drains your stamina) on the hotkey. The moment I left the menu page, I was already surrounded and I had no escape, the only option left was to intentionally surrender to not take any HP damage. Next thing that happened was that Lona's virginity was taken, brutally raped, imprisoned and tortured again. But the bandits screwed up. Their dumbasses left half my items in the chest next to Lona, including food. And you do not want to be against a maxed level assassin Lona who can make deadly traps from thin air.
Looking back on this experience, I would have 100% died if I just tried to fight the bandits straight up, but because I surrender at that moment, I was able to survive and fight another day. And after that encounter, I pretty much always took the safe option when dealing with the bandits overmap encounter (and made sure to slaughter all the bandits for touching my Lona). And it is these small details and gameplay mechanics that really makes me appreciate it. There are so many options you can take and sometimes it is not clear what to do. But if you take the time to learn these small interactions, it makes the game so much better.