Fun idea to use the player's bones as ammo! Altering the player's movement based on the bones they have left is also great, but I found hopping to be a bit more annoying than crawling, so I actually preferred to have one less bone in that case. I also think it should be possible to pick a bone back up if you fire it and miss; I ran out of bones pretty quickly because of that. I personally don't have a lot of skill with this style of game so I died quickly, but it was still fun to play while I lasted!