The game starts out with D-9341, a D-Class personnel, in his cell. After picking up a document containing details of an "exciting one month-working period" in a top secret facility, a Guard opens up the cell and tells 9341 to come out and perform a test with SCP-173. As 9341 arrives, there are two other D-Class personnel. The scientist tells them to approach SCP-173. His voice will be cut off after saying the door controls are broken and SCP-173 will attack. The scientist announces a lock down for the whole facility. Trying to survive the containment breach, 9341 will encounter many different SCPs.
WARNING:THE FOLLOWING SECTION MAY CONTAIN SPOILERS ABOUT THE GAME
- Main article: Gate A
If D-9341 escapes by Gate A, SCP-106 will come out from the ground (if not yet contained) and Nine-Tailed Fox personnel stationed outside will activate the H.I.D. Turret to contain SCP-106. If the player hasn't escaped yet, a MTF unit will approach D-9341. If the player escapes, a group of Chaos Insurgency soldiers will take the player away and the game will end.
- Main article: Gate B
There are two endings at Gate B. If the player has not turned off the Alpha Warheads in the Warhead Silo before the player reaches the control room, a siren will sound and a bright flash from the warhead's explosion will cover the screen at the end of the countdown. After this, the ending logo will appear. A radio transmission will be heard, as a radio operative from helicopter OH-6 requests the deployment of an MTF unit 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 .There might be another ending in a video called "Is there a Gate C?" At the end of it,SCP 682 escapes.
- Main article: Developers
Joonas Rikkonen (Regalis) and his group of developers created this game with the Blitz 3D engine. The game is currently only for Windows and the music is composed by Kevin MacLeod and Tim Morrison. Aaron Mckee (commonly known as TheVolgun) contributed a great deal to the development of the game by being a voice actor for several characters including SCP-049, SCP-990, D-9341, the scientist and guard in the first room and an MTF unit found in a SCP-049 cutscene.
- Main article: Versions
- 0.1 - The first downloadable version. It included the basic mechanics and had some of the SCPs.
- 0.5 (Halloween Update) - In this update, SCP-173 could have a new look via the Console Commands. It also fixed some models
- 1.0 (Main Release) - Added in SCP-066, SCP-860, SCP-939, and SCP-970. It included new models, new sounds, new music, and a harder difficulty.