Initially, it was quite hard because you don't get feedback when you get damaged(mainly cause you have 1HP) and being one shot increased the difficulty a lot, I found myself playing the game by hiding in the corner and just snipping(I did speed-run the first bit and made a jump). And the boss was easy because I was hiding behind the walls and killing them, and I was able to pass through breeze by killing other enemies without entering the room.I'm not sure if this is how you intended the gameplay to go down, but this could be easily solved by giving the player 3-5HP with damage feedback.
I didn't use the mechanics much because of this flaw, but the time stop mechanic along with the dash was really amazing and easy to control. If you tweak the game a bit more, this can be a really good strategic FPS. Nevertheless, I enjoyed the gameplay, the music and the art (this definitely was inspired by Superhot).