Suffocating yourself for long enough causes a noclip event that drops you into the Backrooms. From there, you must travel through five levels to find an exit. Level 0 is the place everyone has heard of — infinite yellow carpet corridors and fluorescent light. Level 1 is the Habitable Zone. Level 2 is Pipe Dreams. The Poolrooms are the Poolrooms. The fifth level, the Infinite Grass Field, is different from all of them.