I gotta say, the art style, music, dialog, and gameplay really gets me. The level design could do some work though. There's a bit too much enemy spamming in areas and there's no real reward for defeating them. There's nothing stopping the player to just run past everything and straight to the boss for a boss fight and win under 5 minute of playtime. (Which I kinda did)
I don't really see why there was a different attack moveset in the beginning of the game only to get replaced by the musical mode immediately after the first enemy appeared on the screen. I do like the movesets to be honest, but I don't really see incentive to change mode and fighting the mass mobs. (I tried in the beginning, but I gain nothing. No experience or anything)
However what this game excels at is definitely how the combat feels, it feels really nice and I actually want to do more battles. Personally I think this kind of gameplay might work better in a roguelike where player can be forced to fight mass of enemies before continuing to the next room/screen while finding the way to reach the boss. In an open RPG level design really need to work better to company the playstyle, and enemy waves need to be rewarding (either by story/key items/etc.)
Really great work tho! I'm really enjoying it. That to be continued is a real evil cliffhanger. Would be great to see more of this.