I feel he probably should have stuck with his older 2d side-scrolling beat-em up formula. He could've easily improved on them like the second Sakura game where he added a counter ability. It would've been nice to improve on the combat by adding different combos, enemies who can retaliate from a stun-lock randomly, maybe even having 2 playable characters. Also, if he got rid of the drawn game overs, I feel as though he could've focused more on the in-game H, like adding more variety or more gang-bangs. Part of the problem with the 2d game-over is that it's consistancy is whishy washy, and I do believe it's someone else he has doing the 2d animations anyway. If he cut that out he could increase his profit.
Sad thing is he has added things that improved on game play but only used it on like one stage or a few enemies. Take the Fighting girl Mei game where he added a different path (which led to nowhere), it's possible to have expanded on that by having unique enemies, boss or a whole secret stage on one of those. Maybe even adding in girls that you can save before they meet a grim fate. Which could also be expanded on by having them reward you with skill points, currency or potions.
I'm kind of ranting but only because I've always loved the animations from the old fighting girl games, and that he can expand on it so much with just a little imagination. I still go back to the old Fighting girls and add challenges like making them a glass cannon, or weak with a lot of health, but Fairy Heart just has no real place in my heart for extra playthroughs. It just seems to lacking charm and is all over the place. I really do hope his next project is better.
*Edit:
One other thing I would love if he changed or added was like a no modesty skill, maybe have it cost a lot of points, but basically it'd allow her to fight even after her clothes got ripped so you're not stuck with just one lame punch. She could still be in a weakend state and not have access to all her abilities but at least she's not completely useless.
Also, just thought of a new challenge. You can only play in the weakend state, only can increase strength and health. Potions would pretty much be spammed.