This one had promise - making a shooter, let alone a survival horror one, in such short time is really impressive. The main issue though is just sound - the entire soundscape feels entirely empty. No sound other than the gun is neat, but it just made the game feel quiet. Without any indication of what route to take as well, you end up wandering around for ten odd minutes before the bomb drops.
I think with some audio for the undead, and maybe some more juicy animation and movement, this could definitely shine as a solid game loop. For something made in four days though, it's not too shabby.
Some quality of life features like a pause menu would also really go a long way.