The rooms in the DLC Karamari Hospital.
The Isolation room (located in the basement) consists of three areas, a small corridor with patients rooms containing two notes about the hospital, the Ghost Cow maze and the exit key/demon child room.
The exit key room is a room found at the end of Monster 5's maze. The room is small and contains one note about Spooky's past and the exit key in the first playthrough of the game, also in the black window of the locked room, you can see the Demon Child.
In New Game +, it is possible to encounter a different instance of the room if the player gets the sword and kill all enemies. In this instance, the Demon Child have a different reaction to the player and a new note talking about Spooky's origin can be found in the place of the original note.
There's a side room in the hallway where you encounter Monster 1. In this room, you encounter a bed in the middle of the room with blood flowing from the bed to the ceiling. Screams of a man can also be heard the closer you walk to the bed.
The Morgue rooms hold several body bags each, with one of them containing the Badge and the other containing Acid. Once the player retrieves the badge and then exits, they will enter a room with body bags scattered around. Monster 2 will then start chasing the player.
Monster 6's Corridor
A long corridor that can be found in the "nightmare" basement area, if you keep walking you will see something white like a small dot in the distance, keep walking and you will be jump scared by Monster 6, or as she goes by her files name "Becca".
The Basement is, seemingly, the last area in the game (not counting Isolation Room). A key to the Isolation Room can be found there. After the key to the Isolation Room is retrieved, Monster 4 will start to chase the player. Monster 3 occasionally appears in the rooms there, when Monster 4 isn't chasing the player.
An area that was added in the July 4th, 2016 update. It seems to continue endlessly.
- The screams being heard in the blood bed room were done by Matt McMuscles from the Youtube channel Two Best Friends.