First off, I want to say I really enjoy the blend of dungeon-crawling RPG with bullet hell platformer for the encounters. It's cool and unique. I like the bright colors and generally I find the aesthetics for the geometric coins and encounter exits to be charming.
I know this a demo and not reflective of how the full game is going to be, but it needs saying the jump sound effect is not good, and the battle music is far louder than what is expected from changing music volume from the menu. This latter point in combination with not being able to access the settings from within the dungeon gets hard on the ears.
The hit feedback for enemies with higher health than OHKO is difficult to see with the bullet hell nature of the player attacks (other than the enemies who experience knock-back). The shield also has no hit feedback and thus I assumed you were supposed to walk into the shield and just tank the enemy attack.
The Sonic Beam and Void Laser are hard to aim, but the Energy Helix just feels like you're cheesing it and unsatisfying to play once the novelty of being OP wears off. It's also sad you can't break vases with the Energy Helix :(
I'm also concerned with how the NSFW elements are going to be incorporated, because I think I'd enjoy them better if they felt cohesive with the core experience. Right now, they feel pretty tacked on and isolated in their implications.
All in all, I am intrigued by this game and wish you the best on developing it further! :)
Btw, think you could put Patchouli Knowledge in it? :3