The Tree House That Never Was

A world of Nothingness that was created by Xemnas to serve as a stronghold for the members of the Organization who reside in Minipeg. It resembles a giant Tree House, modeled similarly to the Castle That Never Was, and is surrounded by a dark sky.

Functions
Each of the Final Seven have their own rooms within the base.

When Luxord is defeated, the group that resides in Minipeg is no longer able to access Saix through the Nobody Channel.

After Xemnas finally is defeated, Kingdom Hearts appears in the sky that surrounds the Tree House.

It is here where the Final Seven collectively receive their Hearts at the completion of Kingdom Hearts.