I gotta say, I was not quite prepared for this to be as effective as it is.
After all, it's yet another abandoned asylum, yet another found footage, yet another dark hallway laden building necessitating a flashlight. But I have never been a believer that you must always reinvent the wheel. You simply have to oil it well to make them turn smoothly. That's what this does.
Your employer's casual tone and the sudden absolute relentlessnes of it creates a damn fine horror experience very quickly. It's not "new"... but it sure is delicious!