(this is from backrooms wiki)

The Backrooms

If you're not careful and noclip out of reality, you'll end up in the Backrooms, where it's nothing but old moist carpet, the mono-yellow, the background noise of fluorescent lights at maximum hum-buzz, and six hundred million square miles of empty rooms to be trapped in.

Levels

Click on a level to go there.

Levels

Level 0 "The Lobby

Level 0.01 "The Exit"
Level 0.1 "The Danger Zone"

Level 1 "The Habitable Zone

Level 2 "Pipe Dreams"

Level 3 "Electrical Station"

Level 4 "Abandoned Office"

Level 5 "Terror Hotel"

Level 6 "Lights Out"

Level 7 "Thalassophobia"

Level 8 "The Cave System"

Level 9 "Darkened Suburbs"

Level 10 "The Bumper Crop"

Up Coming Levels

Level 37 "The Poolrooms"

Level 188 "The Courtyard of Windows

Level 974 "Kitty's House

Level 399 "The Neon Arcade"

Level 11 "The Endless City"

Level 12 "The Matrix"

Level 13 "Vitrum Madness"

Level 14 "Inhospitality"

Level 15 "Futuristic Halls"

Entities

Entity 1 "The Cameraman"
Entity 2 "The Windows"
Entity 3 "Smilers"
Entity 4 "Death Moths"
Entity 5 "Clumps"
Entity 6 "Dullers"
Entity 7 "Jerry"
Entity 8 "Hounds"
Entity 9 "Facelings"
Entity 10 "Skin Stealers"