Cool idea! I like the challenge introduced by the lack of damage done by the bullets and the controls feel nice, but slightly off - in a good way. My main issue is the lack of feedback when an enemy, or you for that matter takes damage... I took 3 health before I even realised, and I didn't realise I was actually hitting the blue enemies for a while because they weren't showing any sign of damage... Either way cool game, and I hope my thoughts helps you in the future!