Vault 8166 rumor

What Is Vault 8166?
 Vault 8166  is rumored to be a hidden server on  Roblox  where unexplainable things beyond usual are occurring. It is allegedly a secret map ran by unknown hackers which have the ability to watch or monitor activity going on between users. It is said that anyone who goes there can gain access to certain information on  Roblox  and use the installations, GUIs and programs to bypass site encryption. This facility is believed to be the birthplace of the most dangerous exploits that have ravaged certain games. Software, bots or viruses are also stored here that are placed and hidden into Roblox models or plugins. 3rd Party sources can also have access to the game through a smoke detector hidden in the vault.

On 9/16/2020 the public version was released. The UI panels within the facility cannot be accessed and it is implied that all connections to a hidden API network have been disabled. The facility is divided into multiple "levels" but only level 2 and level 7 have been accessed as of date.

The First Mention Of Vault 8166
On November 15th 2016, an anonymous user created a thread on the  Roblox  talk sub-forum. This user was claiming to have accidentally gotten onto this "unknown place" while testing out a teleporter for a game. The thread was a brief summary on how "evil is operating behind our eyes", and that there is a place where dangerous people are gaining access to user profiles and other information as we speak. This secret place was referred to as "Vault 8166". A few hours after the thread was posted, word went out. Mysteriously, the thread was nowhere to be found, along with the user who posted it. The thread may have been taken off by moderators. If not, something else was at work and it wanted the forum thread gone.

The 2014 Exploit
Vault 8166 was created by an exploit, the exploit was found in late-2013 by a friend of a developer at roblox, that managed to get access to his friend's computer, then he injected a payload into one of the roblox servers to get remote access. Then, in early 2014, he and his friends generated an internal, encrypted roblox dedicated game server with connection to hidden API Networks also generated by the exploit. Then the exploit was removed before being found by the developers, Vault 8166 was born. In 2020 the server got split in more than 1000 files and spread across different Roblox servers, making it more difficult to be located; this caused the game to move to a new account with stronger encryption. The account is still yet to be found.

Two Users Attacked By An Unknown Figure
In late 2016, a user submitted footage of what seems to be a hallway of Vault 8166. The time and date this was recorded is unknown. It starts out with a hallway full of computers with switching screens that resemble codes. It also contains red flashing lights, a strange white room at the end and a poster containing a skeleton saying "Warning, we are watching you". Two Robloxians, both of which resemble a common exploiter avatar, walk into the middle of the hallway. One of them is colored black, has a particle emitter and red fire. The other is just colored red on the head and has red arms. Neither of the nametags are visible. They stop and take a look around, and out of nowhere a strange skinny figure with large legs comes out from behind and starts running at them while waving its arms. Both characters start panicking. You can see one of the players reacting by a jump. Right when the figure reached them, the video suddenly blacks out and starts flashing randomly. Apparently an extended version of the footage exists, and in that footage the body parts of the player on fire go everywhere while the one colored red runs away in fear.

The Guardian
'The Guardian' is the figure seen in the original footage, Its a skinny figure with a black fire which was attacking the user's you seen in the original footage. The Guardian does not ban your account but kicks you from 'Vault 8166' Before you get too far into it.

Trivia

 * The numbers in the title are the first four numbers of 1x1x1x1's user-id. But, it is unknown whether 1x1x1x1 is affiliated with Vault 8166 or not.
 * The public server doesn't have a game profile page, but the portal can be found here here.