Scott planned this, didn't he? First, he made a troll game, then now, he tricked users into thinking that it is already over, and let some users leave. Then after some admins left, he came back with a new teaser!
So, here are my thoughts on the game. This one will be connected to a part of MatPat's theory, that Golden Freddy is indeed Spring Freddy, so, I advise you to watch him first. (There's a second part of his theory, he's still working on it)
Before you say that Golden Freddy isn't Spring Freddy, here is why I think GF is SF.
1. Golden Freddy might be in suit mode, and that's probably why he can't move, even if he's possessed.
2. Golden Freddy just reused Freddy's model, so, we clearly don't know what he really looked like, except that the teaser shows him. Springtrap, on the other hand, was a new model, and since he looked different, Spring Freddy too, might look different.
3. Springtrap was focused on FNaF 3, so he had to have a newer model, instead of reusing Bonnie's model. Golden Freddy wasn't that focused on the 3 games, so he didn't need a new model.
That animatronic on the teaser must be Spring Freddy, AKA Golden Freddy. Why? First of all, it is very deteriorated, like Springtrap, and it has 5 fingers. The other one is hidden between the 2 other fingers. Also, it has a hat. Freddy is the only animatronic to have a hat. It also has cheeks, and a bowtie. And it also has different wounds, which makes him clearly different from Springtrap.
When would the game probably occur? Because of the 8s and 7s on the website, some of you might think it's on 1987 or 1978. 1987, is a no, because we already had FNaF 2 set on 1987, and we can clearly see that Golden Freddy is not that deteriorated. 1978 is a probable date due to the fact that the Sister Location could have set in this time. 1887, 1878, 2087, and 2078 are big noes due to being far.
Here is a list of the probably important events on the timeline that we haven't seen yet in-game, except for the minigames.
1. Fredbear's Family Diner
2. First Freddy Fazbear's Pizza (Withered Animatronics)
3. Sister Location
4. After the Fire at Fazbear's Fright
So, which among these timelines could be fitting settings?
The Fire. Why? Spring Freddy is in a very deteriorated condition, and it is safe to assume that it happens after the fire.
If the games will focus on the events of 1978/1987, then, any time, as long as it is after these times, will do. There can still be minigames, and whatsoever.
Now, the "Nightmare". What could nightmare mean? Now, this could be related to the setting of the game. What happened at the end of Nightmare mode? The Fire, right? This is probably what nightmare could be referring to.
About the "I am still here" image. That's right. It can refer to Spring Freddy, due to sharp teeth. Springtrap has buck teeth. Also, this could support my claim on the game setting after the fire. He's still there, after the fire.
Also, don't you think that "The Final Chapter" is a fitting title, because it is indeed the final on the timeline?
So yeah, that's just a theory, a FNaF Theory! Thanks for reading.