[Vivisectus]

I have one where I am fleeing through a massive version of my childhood home. It has way more rooms and all the rooms are bigger too.

I am being chased by something I can never quite see, but I know it is quite large, vaguely human-shaped, and that it is terrifying. It is quite close behind me and it is trying to grab me, but I manage to scramble just out of it's reach by darting around corners, diving under tables and slamming doors shut.

Finally, I find my parents bedroom... and it has a lock. I lock it behind me, fumbling with the lock for a terrifyingly long moment, and step backwards. It seems that I have escaped. Then I look in the mirror next to the door, and I see that somehow the stairs to the attic are now in my parents room, right behind me... and the creature is already halfway down the stairs. I have locked myself in with it.