Thank you for the game!
Very impressive work, especially the cutscenes and sound design. Nice atmosphere, too. I especially liked the elevator sequence; it was so strange and out of place, it made me feel creepy in a good way.
With that said, I couldn't say that I've thoroughly enjoyed my experience. The main character's movement felt too jerky and rigid; it actively took away from the feeling of dread and realism. Switches between cameras sometimes felt extremely jarring and unprompted; sometimes a camera view in a room would change, like three times, although the room was perfectly visible from the initial vantage point. In other cases, I could wander what seems to be far away from the camera view, and it never switched to show me where the character is. I found myself stumbling between camera views, trying to find my way further a bit too often to my taste. The "don't make noise" mechanic didn't seem to work. In the toilet scene, I was standing perfectly still and silent, but the dude still attacked me. And further on, zombies seemed to be chasing me around, no matter how much noise I was making (or if I was making any, which was hard to tell too).
I was impressed with the narrative presentation, but the story didn't touch me personally, unfortunately. Maybe I missed something, but I never got how the Issacs' story is connected to the main plot of the game. The final cutscene suggested that the zombie I ran over had some significance, but the game was not good at communicating to me why and what exactly was happening.
On the technical side, I think I had some bugs with the lighting: in the first two levels, it was very flat with no shadows, so the flashlight was completely useless. Judging from the screenshots, this is not how the game was intended to be, so maybe it is something you should look into.
Anyway, sorry for the long and mostly negative review. The amount of work you've done is very impressive, and the game has some good parts in it. Hopefully, my feedback could help you make it even better in the future :)