Good game, here are my feedback on it:
+ I loved the art style! Keep it up with this style, you have something here!
+ The music and the feedback sounds are cool, and fit well the game.
+ Also I liked the puzzle system for unlocking the doors, it is really clever.
+/- The gameplay is really cool and nervous, I like a lot this kind of gameplay, however I was quite frustated by the shoot stamina. It would have been nice, if it was infinite like a shoot'em up.
Overall: Nice work!