One of the game's primary features is randomly generated rooms. All of the rooms in the game are randomly chosen from a set of hallways, chambers, and offices, which are strung together to create the facility. These rooms are divided into three sets: the Light Containment Zone, Heavy Containment Zone, and Entrance Zone. Each set contains a unique set of rooms and hallways that can be randomly generated, as well as its own artifacts and SCPs. Some SCPs, such as SCP-173 and SCP-106, may appear throughout the entire facility. The zones become gradually more difficult as the player progresses; the Heavy Containment Zone possesses more dangerous SCPs than the Light Containment Zone, and the Entrance Zone marks the appearance of "Nine-Tailed Fox", a squad of elite soldiers deployed by the Foundation to recapture the breached SCPs and/or destroy the facility by detonating the nuclear bombs situated throughout. Those soldiers will shoot the player on sight and travel in teams, making them some of the most dangerous enemies encountered in the game.
Along the way, the player can find a wide variety of items to assist them in survival. These include tools such as gas masks, various electronic devices, batteries, and keycards of various levels for operating locked doors. They may also encounter benign or inanimate SCPs; an example being SCP-914, a large clockwork machine which is capable of refining items the player inserts into it into either worse or superior versions based on how its controls are set prior to activation.
Plot
The game revolves around the SCP Foundation, a secretive organization dedicated to containing any anomalous artifacts, entities and locations that threatens the normality of the world. At some point before the events of the game, several of the Foundation's containment sites are attacked by the Chaos Insurgency, a rogue element of the Foundation, forcing the relocation of many SCPs (the designation given to their contained anomalies) to an unspecified site. A Foundation task force known as Nine-Tailed Fox is established shortly thereafter to defend this site from any possible breaches in containment.
The player takes the role of D-9341, a Class-D test subject (usually inmates on death row, who have been drafted to work for the Foundation) who is forced along with two other test subjects to perform tests on an SCP known as SCP-173, a concrete statue that can move at high speeds and attack by snapping of the neck at the base of the skull or strangulation when not in the direct line of sight of a person.
During this testing routine, the site's power and door control systems begin to malfunction, allowing SCP-173 to kill the other two test subjects and escape into the ventilation system while by player control, D-9341 escapes the containment chamber. A site-wide broadcast then announces that several SCPs have breached containment, forcing the site to be put under lockdown. The player must then guide D-9341 around the facility while trying to survive many of the escaped SCPs which roam the facility, including SCP-106 (an entity resembling a decaying old man that may travel through matter and which attempts to drag the player into a pocket dimension to kill the player), and SCP-096 (a humanoid creature that will unavoidably chase and kill the player if they view the creature's face, but which is otherwise docile). The player must additionally evade Nine-Tailed Fox soldiers deployed to recapture the SCPs, as they have been ordered to target and kill any stray Class-D personnel. Later in the game, the player encounters SCP-079, a malicious artificial intelligence inhabiting a microcomputer, and learns that it caused the power outage when several Chaos Insurgency spies gave it control over the facility, resulting in the foundation being busy recontaining it. From here SCP-079 will propose that the player reactivates the door control system, allowing SCP-079 to regain control over the doors, in exchange for helping the player escape the facility. If the player re-activates the door control system, SCP-079 will open the doors to two different exits, Gate A and B. From here 4 different endings can be reached. The first and second endings can be reached by exiting the facility through Gate B. Upon reaching the surface, an alert is sent out stating that SCP-682 (a massive, nearly indestructible, reptilian creature with fast regenerative abilities of which the SCP Foundation has attempted to terminate several times) has broken out of the facility near Gate B and that nuclear warheads, kept in the base as a last-measure containment system, will be detonated in an attempt to destroy it. Shortly after, the warheads are detonated, vaporizing the entire area, including D-9341. At the end screen, a radio transmission will be heard as a radio operative requests the deployment of a task force to scout for remains at ground zero. However, the transmission is cut-off mid-sentence as a large roar is heard, indicating that the nuclear blast was unsuccessful in destroying SCP-682. The second ending occurs if the player had disabled the nuclear warheads while they were inside the facility. Another alert is sent out advising all combat personnel to return to Gate B, with a group of soldiers converging on the player's position. The player is thereby killed as the soldiers open fire.
