|“|| I hear that it's almost never sunny in Silent Hill. And people say that when the fog comes out, strange things happen.
The Fog World or Misty World (shown in the tips menu of Silent Hill: Origins) is the name given to the dimension that lies alongside the Real World and the hellish Otherworld of Silent Hill. The Fog World may be seen as another side of the Otherworld and considered to be part of the same realm or dimension (though in a different cycle), but the exact distinction between the Fog World and Otherworld is unclear. The Fog World has been compared to NREM (non-rapid eye movement) sleep, which is the period before heavy dreaming. 
The process by which someone passes into the Fog World from the Real World is not often touched upon in-game, but each time it occurs, it is typically depicted as a gradual transition, with most characters not even realizing that something is amiss until their first encounter with one of the town's creatures.
In the games, the Fog World appears to be an almost exact copy of its Real World counterpart, except that it is perpetually shrouded in a thick fog and seems almost completely uninhabited. The fog usually tends to be white or light-grayish in color. In Silent Hill: Homecoming and Silent Hill: Downpour, however, the fog has a much darker tinge that is reminiscent of smoke.
While the Fog World is considerably less macabre than the Otherworld, it is still a relatively hostile environment, in part due to the monsters that roam freely. The various locales in the Fog World appear to be in a constant state of disrepair and almost completely deserted, with the exception of the town's monsters and few people. Bloodied corpses and wrecked cars are fairly common sights in this dimension. Its roads often drop off into deep abysses, which prevent any means of escape for its inhabitants.
In the original game, snow falls in this world, while in the film, ashes fall from the sky instead. Silent Hill: Shattered Memories reintroduces the element of snowfall and in Silent Hill: Downpour, heavy rain becomes a common occurrence. In the other installments, the Fog World lacks any of the additional effects listed.
The Fog World is often constructed like a labyrinth, with many normal doors inexplicably jammed or with broken locks, that prevent passage. Also, many doors are locked with their keys hidden in bizarre places; for example, a key can be found inside of a soda can from a vending machine in Silent Hill 3. The Fog World can also expand into nearby towns, such as Shepherd's Glen in Homecoming, in order to punish certain people involved with the history of Silent Hill.
The Fog World in the first game helped to hide the game's graphical limitations (draw distance). However, many players have praised the fog, stating that it created a "spooky" or "gloomy" environment.
Another popular idea is that Alessa Gillespie created the fog to give the world a limited view to visitors, since she herself never saw much of the world around her, and as such, left an imprint which causes the Fog World to appear to other people. The fog could also be a memory of the smoke from the fire Alessa was burnt in at the beginning of Silent Hill: Origins, as Travis Grady says "not fog... it's smoke" when he sees her burning house. This theory intersects the fact that the siren sound heard before the shift to the Otherworld is a print of the medical vehicles sirens that are heard after the burning of the Gillespie house. It could also explain the ashes falling from the sky in the film.
It is also speculated that the reason the later protagonists are exposed to fog is that it is the fog of the mind/memory. This seems the most likely in James Sunderland's case, as he last visited Silent Hill some time before the events of the second game. This theory is supported by the fact that when the Fog World transitions to the Otherworld, everything becomes much clearer, if not more terrifying, which could serve as a metaphor for the character clearing the fog from their mind, and facing/owning up to the terrible truths of their past.
In the film, it is implied that the Fog World was created by Alessa Gillespie and Dark Alessa at the same time as the Otherworld to entrap the cultists. The Otherworld's symbolism of Alessa after she was burned, as well as the symbolism of the change between the two realities representing what was done to Alessa's body, suggests that the Fog World is a representation of who Alessa was before she was burned alive. This would explain the almost total lack of monsters in the film's version of the Fog World, as well as the feeling of abandonment and isolation. According to director Christophe Gans, the ashes in the film's version of the Fog World represent the fires burning in the Otherworld.
Silent Hill 2
Silent Hill 3
Silent Hill: Origins
Silent Hill: Homecoming
Silent Hill: Downpour
Silent Hill: The Arcade
Silent Hill film
|Eric - Tina - Bill - Jessie - Ryan - George - Emilie Anderson - Frank Anderson - Michelle Anderson|
Hanna - Lorraine - Captain - Scott Fairbanks - Greys
|Creeper - Double Head - Greedy Worm - Gum Head - Hummer - Insane Cancer - Mama - Numb Body - Nurse - Phantom - Pyramid Head - Robbie the Rabbit - Scraper - Split Worm - Toadstool - Tremer - Tuberculosis|
|Brookhaven Hospital - Central Square Shopping Center - Jacks Inn - Labyrinth - Lakeside Amusement Park - Silent Hill Historical Society - Spiral Staircase - Toluca Lake - Toluca Prison|
|Flashlight - Fog World - Little Baroness - Monster - Otherworld - Radio - Real World - Siren - Welcome Sign|
|Rose Da Silva - Christopher Da Silva - Cybil Bennett - Dahlia Gillespie - Thomas Gucci - Anna - Christabella - Sharon Da Silva - Alessa Gillespie - Dark Alessa|
|Sister Margaret - Eleanor - Colin - Lisa Garland - Jennifer Carroll|
|Pyramid Head - Creeper - Armless Man - Colin - Nurse - Grey Child|
|Brahms - Brookhaven Hospital - Church - Da Silva House - Gans County - Grand Hotel - Midwich Elementary School - Nathan Drugs - Pete's Bowl-O-Rama - Sacrificial Chamber - Silent Hill, West Virginia - Smitty's - Toluca County Archives - Toluca County Mining Museum - Toluca County Orphanage - Toluca Lake|
|The Brethren - Monster - Flashlight - Manifestation - Otherworld - Fog World - Real World - Siren - Great Knife - Welcome Sign - Brethren Symbol|
|Heather Mason - Christopher Da Silva - Vincent Cooper - Claudia Wolf - Leonard Wolf - Dark Alessa - Douglas Cartland - Alessa Gillespie|
|Rose Da Silva - Dahlia Gillespie - Suki - Travis Grady - Order Soldier - Detective Santini - Mannequin Girl|
|Armless Man - Delusion - Leonard Wolf - Lobotomy - Mannequin Monster - Memory of Alessa - Missionary - Nurse - Pyramid Head - Valtiel|
|All Hallows High School - Brookhaven Asylum - Central Square Shopping Center - Jacks Inn - Sanctuary - Silent Hill, West Virginia - Lakeside Amusement Park|
|The Brethren - Halo of the Sun - Monster - Manifestation - Otherworld - Fog World - Real World - Robbie the Rabbit - Seal of Metatron - Siren - The Order - Great Knife - Welcome Sign|