The link between your ammo and your health REALLY changes the way you play! GREAT IDEA!
Since your ammo is your health, you can't just carelessly shoot bullets hoping that you'll hit the spot eventually. At every shoot I was REALLY focusing on the enemy's movements while trying to dodge bullets at the same time!
Also, the less health you have, the less likely you are to fight! At the end of level 2 I legit made a run for it because I only had one health remaining XD
Oh yeah. It goes without saying but Beautiful art style ! I really enjoyed it! :D