Nice game, I had fun playing it.
Really cool art style, the music fits the game well, the various enemies make it interesting and challenging, you can't really let your guard down even in the earlier stages which is really nice.
My one big complaint would be that the built-in mouse acceleration makes it really hard to play. I don't know if that's here because of the browser but it makes it nearly impossible to aim at the skulls and to track enemies around you, I got totally lost sometimes trying to turn around sharply and stuff