Monster Rat's appearance closely resembles that of a human with both fixed ears, pointy fingernails, stiched parts, and surprisingly, sporting a long, rat tail filled with metal pieces. His face seems to sport fangs, glowing red eyes, and a big nightmarish smile.
Unlike his other counterparts, Monster Rat is a living creature.
Monster Rat starts outside the Bedroom. If the player hears thumping, and sometimes knocking, it means he is either hiding at the door, in the wardrobe, or in the closet. The player must shine their flashlight at these locations to force him back.
If the player does not force him back in time, he will enter the room. He will stand in one of 3 locations in the room, and a purple-blood like effect will appear around the player's view. The player must shine their flashlight at his eyes. This is easier said than done, as Monster Rat will try to dodge his head around to avoid the flashlight beam. After about 10 seconds of this, the flashlight will flicker, and Monster Rat will go underneath the bed.
When Monster Rat is under the bed, the player must look underneath the bed to figure out which side of the bed he is hiding under. If he is on the left, for example, the player must quickly stop looking under the bed and look to the right side of the bedroom. When they hear the sound cue, they must shine the flashlight in the eyes of Monster Rat. Doing this will play an animation of Monster Rat leaving the room, and the cycle repeats.
Monster Rat will jumpscare the player, resulting in a game over, in any of these situations:
- The player fails to shine the flashlight in his eyes enough.
- The player fails to force him to peek out from underneath the bed.
- The player looks under the bed for too long while Monster Rat is hiding under it.
- The player fails to shine the flashlight at Monster Rat's eyes when he pokes out from under the bed.
- The name "Nightmare Rat" was at first confirmed by Emil Macko in this post gamejolt page.
- Emil Macko said that he called the animatronic this way, because "nightmare" describes it pretty well, though it does not look like a "typical nightmare animatronic" from FNaF4.
- Monster Rat is seen in his first, unwithered/non-nightmarish version on a picture with a boy, in the trailer of Five Nights at Candy's 3.
- It is possible to prevent Monster Rat from going under the bed, though this might be a rare chance.
- Due to Monster Vinnie's nearly impossible difficulty, the chance could be very rare.
- Monster Rat can be considered an opposite to his Animatronic Counterpart, since in the previous installments, Rat was always the last to become active.
- Just like the Five Nights at Candy's teaser image of Rat, you can see what appears to be Vinnie's buttons above Monster Rat at the end of the Demo.
- This may suggest that RAT/Monster Rat and Vinnie are somehow connected with each other.
- Much like Candy in Five Nights at Candy's, Monster Rat has 3 jumpscares.
- This can be a reference to how Monster Rat is the main character of the game, same as Candy being the main character in the first one.
- He also has 3 different jumpscare sounds, that correspond to his different jumpscares.
- On Reddit, Emil Macko had said he changed to names of Nightmare Rat and Nightmare Cat to Monster Rat and Monster Cat for two reasons: One they are not meant to be animatronics and Two they're meant to be living creatures.
- Starting from 2016-11-25, Nightmare Rat and Nightmare Cat's name had officially been changed to "Monster Rat" and "Monster Cat".
- This correlates with a saying that states Whatever you imagine to be real, is Real.
- Monster Rat's eyes look similar to Nightmare's from Five Nights at Freddy's 4.