The first two levels were good... the puzzles worked well and introduced the mechanics... the visuals were clear and easy to parse...
But the third level (the platforming one) was kind of a pain. Pushing blocks with your face is kind of a pain, and first-person platforming is kind of a pain (if there aren't parkour mechanics). I'm surprised my solution of pushing the two blocks on top of each other worked, it felt like if anything went wrong I'd have to restart the level again. Is that level necessary?
I'm curious about where the final level is heading, with the enemies who target you. I'd like to see it all come together. I'd like to use an enemy corpse to activate a button... but then... I suspect the gun isn't ever going to work.