COOL!
Such a unique premise and well executed. I found it was challenging but definitely possible with a few tries, and definitely keeps you on the edge of your seat. The in-game text, the ripples, the black on black were all very satisfying aesthetically, and I appreciated that it was tuned so that shooting directly into a wall your standing next to doesn't kill you. It made me tune my strategy to try to shoot at acute angles relative to the wall I was walking parallel to.
I found the best way to play was moving through meditatively and cautiously since the environment was unforgiving. I wonder how this game would feel with a limited amount of health and some kind of time pressure (not sure if it'd be what you're going for, but I just think it'd be an interesting twist)