Setting

Players control a man in a surgical mask. This character is an isolated survivor of an infection which has turned his city's (and possibly the world's) population into aggressive, shambling mutants. With limited food and an increasingly fragile mental state, the player character must be guided outside his apartment to scavenge and explore. There are no indications that any other survivors exist except for a note which states that there are other survivors on the opposite side of the apartment building, and a man simply called "The Director".^[4] Time progresses, in the form of days, as the player saves, by the means of sleeping in the man's apartment (and experiencing strange dreams or hallucinations, by taking either blue or green pills), which appears to be the safest area in the entire game.

Throughout the game references are made to the survivor's state of mind. It is possible to have discussions with a toy cat, or talk the main character's problems out with a real cat that can be adopted; strange characters such as a man with a box on his head are encountered. Rooms may change appearance upon being revisited; making a wrong turn may result in a strange scene. It becomes difficult to interpret what is real to the survivor and what is hallucination.

Plot

A nameless man in a surgical mask (referred to in the game as "You") has been living in an apartment for an unspecified amount of time after a disease has turned most of the city's inhabitants into mindless zombie-like monsters. The man is alone and unsure if there are any other survivors. In the opening scene, which is a dream, he meets a man with a box on his head and a girl in a blue dress. At the end of this dream, a man wearing blue with a single gunshot wound appears before the survivor wakes up.

In the waking world the man is out of supplies, and is forced to explore for food, weapons, and other survivors. Following leads picked up from his radio, annotated maps, and discarded diary entries, the man explores the apartment complex infested with monsters. He finds a card with a radio frequency, which he uses to discover another survivor, a man who refers to himself as "The Director," who occasionally provides the man with flares, bullets, human and cat food, kitchen supplies, and electronics.

Though their encounters are brief, the man and The Director begin to form a friendship. He also encounters multiple times the girl from his dreams, who he claims seems familiar. As he explores, a series of bizarre, seemingly paranormal events occur and it seems the man is struggling with his sanity. After many days spent possibly dreaming of the man in blue or the man who wears a box, and many nights spent in confrontation with a large and aggressive monster, the man is able to leave the apartment safely, and begin to explore the city.

The Director tells him that he is going to leave the city. Determined to get past a crashed bus, the man gathers supplies so he may open the bus door. Not sure what to expect, the man is attacked by a large, screaming monster with scythe-like arms known as Mother. After a brief confrontation, the monster flees and the man finds The Director mortally wounded. In their final conversation, The Director tells him that he should go to the hospital, and gives him the hospital's security code.

Upon arriving at the hospital, he finds a clipboard with his name on it, even though he claims he has never been a patient there. He proceeds to the room indicated on the clipboard where the door shuts and he becomes trapped. Seeing nothing else to do, he takes a blue, red or green pill (depending on how the player progressed through the game) at the bedside and then goes to sleep. The scenes leading to the final one are different depending on the choices that the player has made throughout the game. However, the final scene always contains a shot of the man and the girl in the blue dress having a conversation and looking out upon the city.

In the Director's Cut, assuming the player has the maximum mental health score, and does a multitude of other things throughout the game, they will get a different ending, where the character walks down a hallway in the hospital while hiding from the girl in the blue dress, who appears to be infected and is crawling across the ground. It will still end with the man and the girl looking out to the city. A joke ending also exists, where the man dances at a party (which was likely a hallucination).

Endings

Blue Ending

In the 'blue' ending the player encounters the man who had gunshot wounds in the game's opening. The man in blue taunts and laughs at the protagonist, leading the man to shoot at him. After shooting, the man's appearance changes to resemble the man in blue, whose gunshot wound is fully healed. The game concludes with a clear view of the devastated city, followed by a conversation between him and 'her' sitting on a hill. This ending suggests the man's possible descent into further madness, or the indifference of the main character to his problems and sanity.

Red Ending

The 'red' ending is an alternate outcome to the previous ending and is triggered if the player's mental score is at the absolute lowest possible. After shooting, the man's appearance changes to resemble the man in blue, after the manifestation of the similar gunshot wound on the protagonist. The game concludes with a clear view of the devastated city, just like in the 'blue' ending, followed by a conversation between him and 'her' sitting on a hill. This ending suggests the man's further psychological madness, demise during a coma or possible suicide.

Green Ending

In the 'green' ending, it is suggested through cryptic and brief flashbacks of conversations that the woman in blue was a sister, spouse, or girlfriend to the man and that she had possibly died in some form of accident or illness (although it is implied that it could be the result of a car bomb, judging by the deprived environment in the city and several references to war within the game). It is at least hinted that in living through survivor's guilt, the man goes through a psychotic episode and is admitted into a psychiatric ward in which he experiences the game up until that point as an insane musing - combating both the violent nature of himself (the man in blue) and his imaginings which serve to pull him away from the truth.

White Ending

Available only in the Director's Cut, the 'white' ending is an extension of the green ending and is possible only on or after a second playthrough. By accomplishing various obscure goals throughout the game and attaining the highest possible mental score, the player can unlock a different door in the hospital, leading down to the basement. There, the nameless man must avoid legless versions of the girl in the blue dress, as they chase him through a hallway that becomes increasingly organic. Finally reaching the end, he ends up in a hospital room, with a glass of water to be taken. Upon drinking the water and going to sleep on the bed, the nameless man has a heartfelt conversation with a healthy version of the woman in blue, followed by scenes largely similar to those seen in the 'green' ending, implying that the man had finally overcome his survivor's guilt and can move on at last.

Yellow Ending

Available only in the Director's Cut, the 'yellow' ending is also only available on a repeat playthrough. By completing a series of specific tasks and also attaining the white ending on the previous playthrough, giving a particular item to the first NPC the player meets will unlock a "joke" ending where the nameless man decides to simply dance his troubles away at the NPCs party instead of completing the game's tasks again.