Excellent game! Very new and interesting concept - I, personally, have never played anything even remotely similar to this game, so big points for originality! The eldritch/forbidden legend theme is always fun, too (but that's just me)! :D
There are a few things that irk me, though:
For one, I ran into a quite serious bug, in that at some point, I apparently "dashed" into a side wall at just the right velocity, and hit at just the right spot, I clipped INTO THE WALL ITSELF. My Heart-guy-character (lolwut) was then stuck in his/its "hit wall on the right side" animation, and he just powerslid down, right through all the subsequent levels... Yes, I really mean through the levels. I had no choice but to refresh the page. Pretty big bug, if you ask me; so I would advise you "squish" it, if and whenever possible. ;P
Another thing that may or may not be a "bug", per se, is that the Key of Life powerups don't stack. That's just the lazy, casual gamer in me complaining; that may just be a design choice that I simply don't agree with. Ergo, there's really no pressure to fix that one.
Sorry I can't be of more help - both in terms of the specifics of how I encountered the first bug, and in terms of giving an overall limited review.
In any case, though, kudos on the pioneering beyond the the traditional "dungeon crawler" genre!