[1] The game is set on a futuristic space station; however, the location of the in-game world can differ depending on the server that is being played, including a spacecraft and an exoplanet.

At the beginning of each round, players choose or are assigned a specific role on the station, such as a medical doctor, engineer, security officer, chef, or scientist.

Additionally, depending on the server, the player can change their character's 'intent' between four different states (Help, Disarm, Grab, Harm), which will further influence actions taken.

[4] Optimally, all players spawn at the beginning of each round and perform their jobs, not accounting for human error and malicious intent.

[5] Antagonists can range from mostly normal characters with certain malicious intentions, rogue artificial intelligence, and a wide assortment of monsters and enemies, such as Changelings, Xenomorphs, creatures of Lovecraftian horror, assassins, and death squads armed with nuclear weapons.

Examples include Goonstation, originally created by users of Something Awful (who are collectively referred to as "goons"),[6] CM-SS13 (with CM standing for Colonial Marines), a server inspired by the Alien franchise,[7] /tg/station 13, originally created by members of 4chan's /tg/ or "traditional games" board[8] and Paradise Station, a popular generalist server with a large Russian offshoot.

Nanotrasen's influence and power have effectively made them a government entity, but it is often left ambiguous as to whether they are good, evil, or a neutral party (depending on the server).

Due to Nanotrasen's immense stature and massive monopoly on plasma, it is targeted by an array of third-party aggressors.

[13] A large number of promising community efforts to remake SS13 have been started over the years due to longstanding frustration with SS13's closed-source engine BYOND and low quality of code.