Here a Little Bit of cube-1's backstory:
He was just a Cube version of C-1, had no purpose whatsoever but to kill other cubes, but one Day, he had ENOUGH. And decided to destroy a master core, causing for his own dimension to collapse and granting him his Godly powers, C-1's dimension is just to remind Cube-1 of what he used to be and to protect his inspiration, and to create many More dimensions for C-1 to stay in a good mood.