Thank you for your feedback :) I used Game Maker for this game.
Yeah, I'm not really well used with the combo guitare VST + Distorsion effect (plus i'm using free cheap stuff, if someone have some recommendations that cost no money, you're welcome).
I'm not sure to understand what you are talking about when you say that the background is muddy to you, like, do you think there is a rendering issue ?
Speaking about the blood effect: it's not a sorting issue, it's intended to be that way, like some sort of HUD effect :)