Sub-levels are located between two certain levels of the Backrooms. Below, there are listed all the known ones. Feel free to add more.
Normal Sub-Levels
Level 0 “The Lobby”
- Level 0.0 “The Giant Room”
- Level 0.00 “Future Void”
- Level 0.01 "A house of a party family"
- Level 0.1 “Danger Zone”
- Level 0.2 “Cognito-Halls”
- Level 0.22 "Fully Remodelled"
- Level 0.3 “The Unfinished Mansion”
- Level 0.4 “The Crimson Tunnels”
- Level 0.5 “The Cubed Space”
- Level 0.6 “Hotel 0.6”
- Level 0.7 “Claustrophobia”
- Level 0.8 “Housed Terror”
- Level 0.9 “The Maintenance Tunnels”
- Level 0.10 ''The Rotting Lobby''
- Level 0.45 "The Big Room" (its Level 0.0 tho)
- Level 0.9223372036854775807
Level 1 “Habitable Zone”
- Level 1.001 "A Chilly House”
- Level 1.05 “The Small Hallways”
- Level 1.1 "Broken Halls"
- Level 1-1 "The lost concrete"
- Level 1.2 “The Abandoned Mansion”
- Level 1.3 “The Core”
- Level 1.4 "Hallways Of Hallways(real name is unknown)"
- Level 1.5 “Inverted”
- Level 1.7 “Trashed Forest”
- Level 1.8 "Supermarket of Reality"
- Level 1.9 ''Something Is Wrong(real name is unknown)''
- Level 1.337 “Colored Hallways”
- Level 1.212121 ''Brightness''
Level 2 “Pipe Dreams”
- Level 2.4 “Gated Corridors”
- Level 2.5 "Submarine Problems"
- Level 2.6 “The Wooden Tunnels”
- Level 2.75 “Apeiro Vestibules”
Level 3 “Electrical Station”
- Level 3.2 “Wired Industry”
- Level 3.3 "Deeper Zones"
- Level 3.14 “Pi Room”
Level 4 “Abandoned Office”
- Level 4.1 “Garages & Pipes”
- Level 4.5 “Whispering Halls”
- Level 4.10 “Infested Office”
- Level 4.82 "Dreadful Workplace"
Level 5 “Terror Hotel”
Level 6 “Lights Out”
- Level 6.05 "The Blenderrooms"
- Level 6.1 “The Snackrooms”
- Level 6.2 “The Thrift Store”
- Level 6.22 “In, and Out”
- Level 6.3 “The Gun Store”
- Level 6.66 “Cutting Deeper”
Level 7 “Thalassaphobia”
- Level 7.2 “Sunken Titanic”
- Level 7.4 “The Small Bathroom”
- Level 7.5 “Screen Saver”
- Level 7.7 “Buzzing Beehives”
- Level 7.𝘓 “Opposite Oceans”
Level 8 “Cave System”
- Level 8.3, "Gemstone Cave"
- Level 8.6 "Martian Caves"
- Christmas Caves
Level 9 “Darkened Suburbs”
- Level 9.1 “Snow Suburbs”
- Level 9.2 “Cul-De-Sac Chaos”
- Level 9.3 “Lost Apartments”
- Level 9.4 ”Lavender Puzzle”
- Level 9.5 “Foggy Forest”
Level 10 “Infinite Field Of Wheat”
- Level 10.1 “The Breakroom”
Level 11 “The Infinite City"
- Level 11.1 "The Aesthetic City"
- Level 11.2 "Brightly lit City"
- Level 11.3 "Graffiti Street"
- Level 11.5 “Town”
- Level 11.6 “Infinite Parking Garage”
- Level 11.11 “The Fake Reality”
- Level 11.72 ''Unnamed sub-level''
- Level 11.111111111111111 “Remodeled City”
- Level 11.011 "The Mall"
Level 13 “The Apartments"
- Level 13.13 ''Halls of El Dorado''
Level 15 “Futuristic Halls”
- Level 15.3 “The Light Neighborhood”
Level 17 “The Cargo Ship”
- Level 17.2 “Coastal City”
Level 18 “Memories”
- Level 18.3 “The Woodlands”
Level 36 “The Airport”
- Level 36.5 “The Plane”
Level 41 “Detention Halls”
- Level 41.1 "The Room"
Level 44 “The Alternate Reality”
- Level 44.5 “The Exhibits”
Level 46 “The Infinite Desert”
- Level 46.2 “The Temple”
Level 88 "Atlantis' Aquarius Dining"
- Level 88.2 ''School bus''
Level 124 "The Purplerooms"
- Level 124.1 "The Dreamzone"
- Level 124.2 "The Nightmare rooms"
Level 189 "Public Bathroom Terror"
- Level 189.1 "The BathHalls"
Level 312 “Gloomy Gateways”
- Level 312.8 “Gentle Sandstorm”
Level 365 "Bowling"
- Level 365.2 ''BOWLING DREAM''
Level 375 “TOTALLY Normal Restaurant”
- Level 375.01 “The Security Room”
- Level 375.1 “Red Road”
Level 679 "The Dark City"
- Level 679.2 "The Infinite House"
Level 777 “The Jugdement Day”
- Level 777.3 “End of The World”
- Level 777.5 “Event Town”
- Level 777.9 “The Luxury Trip”
Level 858 "The Infinite Aquarium”
- Level 858.1 “The Abandoned Aquarium”
Level 1000 "The Campground"
- Level 1000.1 "Almond Lobby"
Level 1021 “Playground of Death”
- Level 1021.1 ''Infinite Enities''
Level 1045 "Latinoamerica"
- Level 1045.2 "Suburban Hell"
Level 1065 “Claustrophobic Bathroom”
- Level 1065.1 “Corrupted Forest”
Level 1205 "The Purple Space?"
- Level 1205.2 "The Purple-Poolrooms"
Level 1472 “Void Maze”
- Level 1472.1 "Balance Yourself"
Level 1919 "The Safe Resort Hotel"
- Level 1919.1 "Basement of Nightmare"
Level 2508 "Make us whole"
Level 3008 "The Quadruple Rooms"
- Level 3008. "The Darkrooms"
Level 3999 "True Ending"
- Level 3999.1 "NEED TO MOVE QUICKLY"
- Level 3999.9 "The Glitched Arcade"
Level 876786 "Unexisting Level"
- Level 876786.9134 ''Your favorite place''
Negative Sub-Levels
Level -0 “Untextured”
- Level -0.2 “When You Look In The Mirror”
- Level -0.12 “The Secrets That Don't Leave”
- Level -0.314 “Depths”
Level -1 “Glitched Halls”
- Level -1.1 "Doorways"
- Level -1.96231.7 "The Strange Elevator"
Level -2 “Overflow”
- Level -2,1 "Hotel Freedom"
- Level -2.5 “Main Gateway”
Level -4 "Carbon Tunnels"
- Level -4.1 "Under Maintenance"
- Level -4.2 "The Forest"
- Level -4.6 "Cardboard Box Maze"
Level -6 “Mystery Mines”
- Level -6.3 “The Fallenrooms”
- Level -6.4 “Paradise...?”
- Level -6.5 “The Super Snackrooms”
Level -33 "Lukewarm Hotel"
- Level -33.1 "The Poolrooms"
Anomalous Sub-Levels
Level ' “Liminal Neighborhood”
- Level '.1 “Dangerous Place”
- Level '.2 “The Backstreet of Many Stories”
- Level '.3 “Corrupted Neighborhood”
- Level '.4 “Running is the only way”
Level ! "Run For Your Life!"
- Level !.1 "40404040 aIRLINES"
- Level !.2 “Unnamed Sub-Level”
Level SYNTAX ERROR "The Test Level" (Level 40404)
- Level SYNTAX ERROR.1 "HTTP 404 NOT FOUND ERROR" (Level 40404.1)
- Level SYNTAX ERROR.2 "Non-Euclidean Deathzone" (Level 40404.2)