Is speculated to take place at around the same time as FNAF 2.
Scott Cawthon posted a poster on his website with the headlines, "Canceled due to leaks." People began to assume that the game was indeed canceled. However, a fan brightened up the picture's resolution and revealed text in the background that revealed hints that the canceled headline is actually part of the game's story
As he clicked repeatedly on an in-game icon that played HandUnit's line "Exotic Butters" repeatedly, YouTuber Markiplier commented that he wondered how long it would be before someone did an "Exotic Butter" remix. Within 24 hours, dozens of fans had created dubs on YouTube featuring the silly phrase.
Baby appears in FNAF world, and vaguely in the book made by the creator, Silver Eyes. A man, also owner of Freddy Fazbear's Pizzaria, is very depressed and suicidal after the Purple Guy has killed his son. He then writes a note saying, "I'm sorry. I couldn't stop her." He then programs an animatronic, (supposedly Baby) to kill him. We see the words, "The show will begin momentarily. Please stay in your seats." We then see the man on the desk with blood spilling. The screen goes dark and we see a pair of eyes. (Also supposedly Baby)
Just like the FNAF games had 5 nights plus 2 bonus nights, 6th and 7th, The FNAF games have 5 main games (FNAF 1 to Sister Location) and two "extra" games, Freddy Fazbear Pizzeria Simulator and Ultimate Custom Night.