Apart from very rare instances; Level 0 is very repetitive. Where it's nothing but the stink of old moist carpet, the madness of mono-yellow, the endless background noise of fluorescent lights at maximum hum-buzz, and approximately six hundred million square miles of randomly segmented rooms to be trapped in. Although Level 0 is mostly made up of randomly segmented rooms, hallways and a few flights of stairs; some cracks on the wallpaper can be found occasionally, showing that maybe people tried to escape this level. Some walls have outlets, but most of them are useless. Rarely, cameras can be found on the ceiling. You can also rarely find groups of rooms stained blood-red instead of mono-yellow, and random rooms filled with decorations and other miscellaneous objects. There are also some pitch-black rooms, and every now and then you can hear whispers. It is by far the safest level in The Main Nine. Interactions with entities are rare, but can happen. The known entities on Level 0 include Hounds, Dullers, Facelings, and rarely Lighters. No-Clipping through a red wall in Level 0 will take you to the closest ceiling to that wall. You can practice No-Clipping in these areas.
Colonies and Outposts
There are currently 14 known colonies and outposts on Level 0 of the Backrooms.
The Level-0 Mystery-Solvers
This group has a population of 122 people.
Most of them are scientists.
Iconic humbuzz found in Level 0
Is rumored to be a branch off of The Backrooms Analytic Squadron on Level 4.
Fort Blake
Used to be a major base of operations for the Insurgency, but was destroyed after a battle with Camp Blastdoor.
What's left of it is controlled by a looter group known as "The Rascals".
Stevie-Town
Only 12 or so citizens.
Led by a man named Steve, who acts as the colony's Sheriff and Mayor.
Open to trade survival equipment, etc. night-vision goggles, almond water, first-aid kit, etc.
Has a small hospital, police force, and fire department.
The "Tom's Diner"
Resides Tom, as the name suggests.
Was a chef before no-clipping into the backrooms.
Has food supplies that could last for another 2 years.
Tom is a cheerful and optimistic person.
The Lucid Group
A population of 8 people that No-Clipped while dreaming.
Known to no-clip to different levels and out of the Backrooms.
This group is not confirmed to be real, as only one person has mentioned it, furthermore, the person refuses to reveal the location of the supposed group.
Guide Outpost 01
The biggest remote outpost of The Tourism Guide.
A general population of 80~86 (travelers and by-passers not included).
Always moving, and relocate every few weeks.
Allows new people or by-passers to have a rest inside, or trading.
Good defense and weaponry.
Can recruit new members inside.
Have search and rescue teams ready on standby in case of an emergency.
Union
Population of 362 people.
Friendly people reside here, trading is open.
Has a guarding force outside of the walls to defend the settlement.
The settlement owner is Daniel.
The leader of the guards is Luke.
There are people called level guides who help tell you what happens in different levels
They excel in defeating entities but it is currently unknown on how they got their weapons.
As it states in their name they are a group of 101 survivors
Very little is known about them but there are rumors about a branch of them in Level fun.
Entities
The chances of finding entities in Level 0 is very rare but if encountered they can be very dangerous, if you see what you think is a wanderer, is not a human.
Leaving Level 0
It is very simple to leave. Just exit using an entry point or use your own entry point to go back. Although, exiting through an unknown entry point could lead to even worse places in the Backrooms. If you spend at least 4 days in this level, you will end up in Level 1. You can rarely find a fire exit, and end up in Level 1. You can also break through the floor to go to Level 27. If you find a scratched wall, which is extremely rare, it is weaker, and breaking it will transport you to Level 111. Breaking one of the lights results in a small chance a tunnel will appear, transporting you to Level -12. If you wander long enough you can get to the Manila Room, Hallway ZZX, or Room 0. You can take an elevator that leads to Level 153, or Level 152 or No-Clip through a broken, damp wallpaper to enter Level 251. Or by entering a white door in to enter Level 251. If you punch a hole in a wall in this level, and go through it, it will send you to Level 4002.
If you play with a black doll it will send you to level Level 7453. No-clip into a moist spot to enter Level 4000. It was recently discovered that staring at fluorescent lights for too long in any level can send you back here.
Entering Level 0
It is really easy to get here. The most common way is to No-Clip out of reality in the Frontrooms. In Level -1 just take a door that goes to Level 0. In Level 49, you will be sent here if you don't meet the requirements. You can get on The Dark Metro to get to Level 0. You can also get here from Level 999. You can also get here from Level 27. You can get here from The Hive by heading down a tunnel. You can also hop into a painting that resembles Level 0 from Level 29. In Level 34, you can go up the sewer grate to get here. If you go into the employees only section in Level 40 you can get here. Also, if you fall through the floor of the catwalks in level 90 you will end up back here as well. In Level 99, if you go through one of the doors you can get to here. In Level 202 you can enter a mono-yellow skyscraper. If you noclip in a corner of Level 433 you will fall through a dark tunnel leading here. In Level 2, you can break a cracked floor to get here you can also enter this level from Level 666 or wait 96 hours or 102 hours on Level 1205.2 to be transported to this level and theres a chance you entered this level by going a sign saying "Empty Office" from Level 251 and a chance to enter Level 4. If you No-Clip through a box in Level 1051, you will end up here. The door labeled 0 in The Hub will take you there. In 9007199254740993 making it to the nether Hub enter a door and mostly will take you here.