Pretty nice. The sound effects and ambience rather than music really give it a zenlike feel. Although I've starting to see the "game lies by using hidden platforms/items that can only be revealed through a circular aoe effect" crop up a bunch, I think it was used well here. The zenlike feel i was talking about earlier really contrasts with the difficulty lol. It's the good kind of difficulty that mainly makes you feel like your failures are your fault. The only real issue i have difficultywise is the lack of invincibility frames on the player (getting gibbed in 3 frames for standing too close to something sucks) and the tiny bit of input lag on attacking from what i'm assuming is the sword animation.
Game is, again, well done, though! The backtracking sort of progression is nice, and the artwork (especially the backgrounds) is very good.