This game is pretty fun, although quite difficult (I managed to beat the first floor after a few tries). The pixel art (especially in the intro) is really nice, the music is great (I like the way it changes with the instrument) and the idea of switching weapons with the music is pretty cool. I think some graphical effects (screenshake, particles, etc) when killing enemies would make the game feel much better and a checkpoint after each floor would have been nice :).