Night 8 (7/20 Nightmare) is considered to be nearly impossible for most people, but with the right strategy, it's easier than Night 7 (7/20 Normal Mode). This is mainly because The Rat and The Cat are unable to disable the phones, meaning you can leave a phone ringing all night.

However, the Rat takes the Penguin's place of disabling the Monitor. On Night 8, he does it in less than half a second, a bit faster than the Penguin on 7/20. Every time you switch to another camera, you must click on it and IMMEDIATELY swipe the mouse up to exit the Camera-Panel, then go back in. This is about 95% effective, because the Rat's face may appear when you enter it again.

The biggest opponent here is The Cat. He takes the place of Chester by attempting to reach the player via the vents. On Night 8, it only takes 5 seconds (or 7 bangs) for him to enter it, as opposed to Night 6, where it takes 10 seconds (or 11 bangs). If he gets in, you may as well admit defeat. He will attempt to enter the vent in the room that he is currently in. Say if he's in CAM 015, he may attempt to enter the vent in there, only when you're not looking. Thus, you must try to follow him around the facility with the cameras, avoiding the Rat as described above. This way, you can catch the Cat and find out exactly where he is banging on a vent. Keeping the sound on stereo and listening closely will also help distinguish where on each side, such as CAM 13 from the others, as it is farther up.

If you tend to get the intentionally-added camera glitch where you see the main area instead of the rooms, exit and enter the Camera-Panel again. This mainly happens after the Rat disables the cameras.

If the Rat does disable them, just swear to God hope you can catch the Cat in time. Thus, speed and good-quality headphones are primary to beating this mode.