The Sister Location: When & Where is it in the timeline ?
So with the help of a friend ( @armyofyetis ), the two of us made a theory regarding the Sister Location's Theory regarding its location & placement in the FNAF timeline !
TLDR: The Sister Location is in a theme park much like Disney & it takes place very close to the other games with the exception of FNAF3.
Now I'm just going to divide this into sections & why we think this to be true.
THE PHONE CALLS ( REGARDING THE TIMELINE PLACEMENT ).
The Sister Location was FIRST mentioned in FNAF3 which implies that the Sister Location was before 2023 ( assuming FNAF1 takes place in 1993 + 30 years ). However, the FNAF1 location was set to close after Mike's week & Phone Guy's death probably made closure even earlier than originally planned. The minigames in FNAF3 show the animatronics in a pizzeria that lines up with FNAF1's location, implying that FNAF1's location really was the final location. However, either way, Sister Location has to take place before FNAF1 for Phone Guy to have made those recordings.
HOWEVER, animatronics didn't become popular until the late 1970s - 1980s with Pizza Time Theater with Chuck E. Cheese and Showbiz Pizza with the Rock-a-fire Explosion . . . and if you want to go even FARTHER back, Walt Disney coined the term "audio-animatronics" and started making modern day animatronics in 1963. It's pretty hard to go even further back than 1960s in regards to animatronic technology.
So while it is a LOOSE space, I'm fairly certain that the Sister Location game takes place between the 1970s - 1990s; alongside with the other restaurants. After all, a Sister Location has to have its siblings around.
THE UNDERGROUND
I've heard people state that we are in an underground testing facility or a bomb shelter. Regarding the settings of the FNAF games, it seems strange that Scott would just stray away from the whole animatronic character thing & to me, a bomb shelter seems really far-fetched; especially since animatronic technology became popular in the 1970s. Bomb shelters did exist in 1970s - 1980s due to the Cold War. However, Bomb shelters looked like pods more than anything else. A underground testing facility is possible but . . . what are they testing and what is the purpose of this underground testing facility ?
The answer that we came up with is: underground tunnels.
Many amusement parks have been documented to have underground tunnels & facilities to transport ride parts, people, merchandise, & suits/animatronic characters. The best example of this is Disney's Utilidor system; which has a giant one in the Magic Kingdom, and some smaller systems in its branches; though other parks such as Hershey Park had them too. These tunnels are to prevent the "magic" from being ruined ( according to modern legend ); but its perfectly feasible for safety reasons too such as maneuvering heavy objects & evacuation of guests during times of emergency. IF this is after FNAF4 where the Bite occurred, then it's noted that Fazbear/Fredbear's did TRY to make things a bit safer ( note: the security systems in the Toys ) but . . . we all know how that went.
These pictures are kind of dated but it's still jarring if you didn't know they existed.
THE SIRENS
At the end of the FNAF Sister location trailer, we hear sirens. I've heard people say air raid sirens. But . . . following my previous statement; that just seems odd it'd be war sirens of all things. I'd like to address something else those sirens could be.
They COULD be tornado sirens because air raid sirens & tornado sirens sound VERY similar & there are sirens in theme parks with bad weather and sometimes, sirens are used to alert people of problems ASIDE from weather.
( Volume warning in those links because. You know. Sirens )
HOWEVER, this could be nothing more than a scare effect, similar to the use of sirens in the Silent Hill series . . . which actually DID make sirens in horror famous & common.
"PLEASE STAY IN YOUR SEATS."
This is a rather short point but anyone who has been in a theme park & been on a ride that isn't extremely gentle or doesn't move at all is REPEATEDLY told to "Stay in their seats ". Additionally, this is told in many shows at theme parks for safety & crowd control which would tie in with an animatronic show. Either way, something like "Stay in your seats" is NOT something you would hear in a pizzeria.
"YOU DON'T KNOW WHAT WE'VE BEEN THROUGH." // "ANGER IS RESTLESS"
The vast majority of accidents of theme parks are primarily the fault of the rider . . . but of course, there are quite a few where the accident is the fault of the mechanics. & a lot of times, these rides remain OPEN rather than closed. The ones my friend & discussed were the America Sings! incident at Disneyland which had a rather deadly accident but wasn't closed until much later for reasons unrelated to the accident. However, there are PLENTY of accidents at theme parks all over the world
Fazbear's is KNOWN for corruption & hiding their secrets. It wouldn't be a stretch to say that an incident would be covered up which would anger families, friends, & following the line of the past games, spirits.
Those were just our thoughts about the placement of the Sister Location game ! We shall see if we are wrong or not !