Really cool concept, definitely on the tricky side but a fun challenge all the same. I'd have liked a slightly more forgiving blood timer or blood refill at the start, as I found I was so low on blood I was more focussed on staying alive than purchasing upgrades, but loved the tension and sense of desperation it generates.
The music is great - perfectly in keeping with the game's setting, and sets a great tone for the action!
Sure you're already aware, but there were some unusual glitches with the player character when jumping or running on slopes - not jumping or running on slopes solved it though!
My high score was 63 :)