Buggy, but a good model
I like where you're going with this - definitely brings back echoes of "The Classroom". Keep working on refining it - all in all, a smooth presentation. I noticed a few bugs - first, walking behind the stealth meter was possible, and even seemed necessary for the last level. Second, at the last level I backed away from the guard's vision, and the player model slowly bled back into the tower through the wall - I was unable to control him.
I'd like to see a full game made from this. Again, a good job.