Existing in the first continuity, Center World is a finite-sized universe currently consisting of one beuracratic-looking building that takes up the entire dimension. They possess incredibly advanced technology, more advanced then almost every world in the multiverse. The total volume of Center World is close to the volume of all other universes in the multiverse combined.
Center World has made it their mission to manage to the universes and prevent chaos. They are responsible for making all dimensions easy to travel between: atmospheres are typically identical, languages are mostly the same, there are no lethal changes in physics, and interdimensional technology and magic usually function in every universe regardless of changes in physics and how magic works. There are exceptions, however.
Within Center World is the Fourth Wall. To ensure it doesn't sustain sufficient damage to completely destroy it, Center World swiftly punishes anyone who notably "breaks the fourth wall". This universe is also where the tournament took place, as well as Xartarin's Epic Tales of Awesome (which apparently happens in the far future, when Center World is destroyed).
Center World's leader in a near-omnipotent being named Tielord, who recruits new members via the Spire of Desire. The organization is in contact with most planetary and dimensional gods, and protects them from multidimensional threats (for example, Marcus) in order to protect the Status Quo.
Deimos and Phobos are a black-haired, blue-suited secret agent and a tiny shapeshifting boar respectively. They're sent when Center World needs to directly interfere in a universe.
The Doctor (from Xar Gaiden) is a Center World agent with an unknown role.
Marcus is a former Center World agent.
Mint Celsius and Tatae are currently low-ranking Center World agents. Kunrai and Garen are in kahoots with Center World, sort of like spies.
All members of the organization need to follow certain rules.
1. No interfereing in a universe until ordered to.
2. When visiting another universe, the rules and physics of that universe need to be adhered to.
3. Minimize disruptions. Use of alien technology is discouraged.
4. Always obey the Prime Directive.