Aesthetically and mechanically game looks good, but I have very big concern about difficulty curve. NPCs often leave you with little to no time to react. Some NPCs have placings where it's hard for player to approach safely and shoot them. In some tries I got to NPC and it immediately killed me after I crossed wall. As "hardcorish" as this game is, sometimes I feel like game is cheating on me. I would suggest implementing 3 HP system or lowering NPC's projectile speed, so player has more time to react.
Otherwise, I really like what you're trying to do there! Music and sounds helped me to feel immersed in the game.