This review is for the mobile version of the game
The fighting system is one of the best versions of an Undertale Battle System for mobile. The way the heart moves feels natural yet balanced. The fighting options (fight, check, item, mercy) are all functional and easy to use. The fight itself has several states for the sprites. The bullet patterns are difficult yet fair and surviveable, and the full-screen battle box near the end has special sprites and a unique soul mode with gravity physics that could be used on a Blue soul mode if necessary. I beat it in only 5 minutes, but there's a lot of potential.
The problem is, it's wasted in this context
To be absolutely clear, the game is impressive, the art is good, and I have zero issue with it being nsfw. In fact, I downloaded it specifically because it was nsfw.
But it is also my opinion that any game specifically designed to turn you on is required to be playable with one hand and not be too difficult so it continues to be playable when you inevitably lose focus for a second.
This is not possible for me in this game. Love Maniac has difficult bullet patterns and requires me to touch every part of the screen, meaning I need one hand to hold the phone and one to play the game.
The game itself is very fun to play, I just am unable to get off to it, which I'm pretty sure is the point
Now, the gameplay (bullet hell) and genre (hentai) of the game may fundementally clash, but that doesn't mean the concept is dead in the water. Here's 3 solutions I can think of that shouldn't be too hard to code in the next version of the game.
1. Handedness settings. Ask the player if they're left-handed or right-handed, and consequently move all the important UI (including the battle box) to that side of the screen, so that the player can play the game with just their thumb
2. Add an invincible mode that simply gives you infinite health (maybe call it horny mode or something idk)
3. Make the bullet patterns noticably more forgiving so you don't have to think too hard to avoid them
As for the battle system itself as it currently is- maybe you could make a second, more sfw fangame, where you can fight different Undertale bosses on mobile? It's an incredibly sophisticated system and I feel it'd be a waste to use it on just the one, kinda short battle.
But yeah 10/10 does way more than it set out to do to the point where I genuinely want way more content to play