What are diegetic level connections?
A diegetic level connection is when levels are shown to exist in the same physical space as each other, despite not actually occurring in the same playable space.
While modern technology has made true open-world games possible, in the earlier days of gaming levels were often wholly separated from each other, only connected by a non-diegetic loading screen. However as technology progressed games would begin to use techniques to make their worlds seem more interconnected than they truly were. In 3D games this was often accomplished by including a low LoD / "low-poly" version of another level in the background or skybox of the current level you were playing.
This blog exists to catalog these artistic decisions and show them off to the world.