Unknown Specimen 3, referred to as Spooper in the game files, is one of the new specimens encountered in Endless Mode.
Spooper appears to be a mutant in the ghost costume. He wears black sneakers and a white sheet with eye holes.
As the chase starts, another creature sometimes appears resembling a pink monster. It has a body with a large eye in the middle of it and two arms.
Spooper will first be found standing in front of the exit door of any given room where he might spawn. He turns to face the player extremely slowly. The door can not be entered when he is blocking it, forcing the player to use the axe to destroy him.
Upon entering another room, Spooper will appear again blocking the exit, bloodied from the previous encounter. The player must continue to destroy him with the axe and move to the next room, Spooper becoming more injured each time. After destroying him in his most injured state, entering the next room will begin his chase sequence.
The grimy rooms the chase takes place in are filled with a caustic air which will drain the player's health slowly. During the chase, Spooper occasionally flashes in the room and a pink monster spawns, but doesn't appear to do any harm. Sometimes, the player will fall to the ground and choke up blood, inhibiting movement and depleting a substantial amount of health.
When he kills you, a text will appear:
"Beyond that door is another world.
A world made of dreams...
A world where all your fantasies have come true.
A world full of everyone's sick fantasies.
A world lusting to include you."
"SPOOPER AMB", Unknown Specimen 3's chase theme
- In Arcade machine mentioning Spooky's backstory, there's an image of person in a ghost costume which looks similar to Spooper`s.
- Because the doors aren't disabled when Spooper appears in some rooms it's possible to go around it and enter the next room. Thus Spooper will appear in the state it was in the last room and continue to do so until it's hit or the player enters a save point.
- Sometimes, when the player vomits, there is a chance that a fetus-like creature covered in blood will appear.