Challenging game for me, but looks pretty well executed. One issue I had was that I'm not used to QASD controls and I kept wanting to use WASD. I switched over the arrows, but I'm not used to using arrows with my left hand while my right hand was on the mouse, so I had a really tough time killing zombies (since I repeatedly found myself rushing headlong into the group of them).
But the mood and aesthetics feels pretty well done and I was definitely trying to creep along as carefully as I could, which was fun. nice job.