What route did you start with? In the prologue of the game, just after Flynn lashes out at everyone at Yeeyaw, you get options like:
Follow Flynn, sit with Carl, find TJ, follow Leo and Jenna
Those decisions choose your route (Clicking Follow Leo and Jenna gives you another choice between going after Jenna or Leo)
Some routes have 2 endings and others have only 1 set ending. But there are tiny little jumpscares hidden that only come out if you make a certain choice.
This game has become one of my no.1 fave games of all time, been about 2 months since I finished it and it is not going to be forgotten by me anytime soon, never have I read a game with characters and story so incredible they leave me staring at nothing for 20 minutes on the menu scaring trying to process what I just read in the end. Or crying for 2 hours straight over these characters.
SPOILERS
Flynn's hallucination is best described as that, a hallucination. He is trapped in an endless purgatory after killing himself in the mines. The talk with Sydney was a dream and part of his hallucination, more how he wishes things with Sydney would have turned out if he lived. The monster is more a manifestation of Echo's curse or the traumas of the town. Not any sort of, folk-lore monster.
