I love horror games and this was a pretty cool experience, I love the atmosphere and the music. On level 3 the zombie pretty much pops out of nowhere but the quick respawn saves the day. I didnt really use the whistle and the flashlight at all, I think that wasnt very clear to me or what effect they had on the gameplay.
Maybe with a bit more time you could have introduced this mechancs one by one in a specific scenario to make them more clear.
Great work, please take some time to review my game.