Pedestrians have been known to spawn on Mount Chiliad and fall down its slopes. Due to their coded pathways, they will try to run down to the roads and sidewalks of Angel Pine, but will most likely fall to their deaths, sometimes letting out a scream as they descend.
Some players believe this is the result of a simple spawning glitch, or coding error; similar to the crashing low flying planes near and around the mountain.
Others theorize the pedestrians were intentionally made to spawn on Mount Chiliad and their purpose as "ambient pedestrians" was to either commit suicide or serve as examples of unskilled hikers/climbers.
The Horror Voices
The Mount Chiliad Horror Voices are connected with this myth, as the screams are believed to actually be the pedestrians falling to their deaths.