In a failed loop before, Su Ming'an learned about the concepts of "Two Dimensions" and "Three Dimensions" on the rooftop of Lin Guang.
Two dimensions were like the two-dimensional plane on paper, while three dimensions were like the normal world.
Essentially, there was no difference between these two worlds, except that the two-dimensional world had an additional filter, blocking the "invasion" from other dimensions.
The Dawn System recorded everything in the three-dimensional world, then substituted everyone's brain data into the two-dimensional world it constructed. In this way, those who could not survive in the three-dimensional world could "downgrade in dimension" and find a space for survival in the two-dimensional world.
