It takes place in a gaming machine, and the game was created by Golden Freddy's agony

Basically it was a punishment for the boy with the Chica mask in the bite of 83, he was made by Golden Freddy to have Revenge, and no it wasn't Cassidy

Basically, from what we see, he's in a forest leveling up and facing cute animatronics, But as he sees it, he is trapped in a forest with animatronics similar to Nightmares, To represent this, during gameplay you will sometimes see the adventures turning into the originals