Sound effects and audio are really good. What the game needs most urgently is a bit of tutorial. I had the "tutorial" turned on, but the information I got was very sparse. I figured how to hit (after a while, at first the game looked like it's controlled only by keyboard, so I was surprised that the mouse is involved here). I could not select the weapon. No idea, how to do that. (The weapon symbols are also very small and difficult to distinguish.) The controls are quick and responsive, even in the web play on my Firefox.
Another point I would improve is the geometry of the level design. As far as I progressed, it was all a plain square. It would be more fun if there are things to hide behind etc.
In general, a well done slasher, with a very simplistic but stylish design. Not my cup of tea, as I don't play these games usually, but definitely on a good way, congrats!