Let me just say that I find it very...curious...and interesting...and a host of other things that the framing of the father + daughter + boat + mouth of river into bay + tentacle sea monster is a problem because "so much established fiction (literally just those things 5 scene tags were established) makes it impossible to surprise players (or the GM)."
The premise of the game is that the Ranger was a Ghost of the Past theme. We (neither the player nor myself) knew who she was or where she was or what was going on; effectively her existence was unknown to her. She only had a singular memory (in Backstory below). This is what she gave me to start the game. She authored a little backstory, set some themes, and authored a Kicker (an opening scene rife with conflict) and we took it from the point of her scene framing. This is basically the start of the game (where her consciousness emerges and we begin the journey of finding out who this character is):
Backstory memory/premise:
Last night was my last evening on my monthlong recon patrol. The moon was full as I chanced upon a spectral stag. Thinking it a sign from Melora, my curiosity got the best of me as I followed it deeper into the wilderness. The trees gave way to a moon-washed clearing where the stag revealed itself to be a Satyr. The fey promised to reveal a mystery that had been courting me in my dreams since I was a child. From its longcoat a perfect sphere emerged. I looked into its foggy depths. Sleep took me. I dreamed the same dream...running with reckless abandon in a rain-soaked forest..from what?..to what?..I know not. This time, the rain and the forest...they are real...
(Kicker) The beginning of play:
Moonlight cuts the darkness. Driving rain. Looming redwoods. Where am I? An ominous presence beyond my sight. Bloodcurdling scream. Is that chanting? Relentless fog. Soaked to the bone. Trees tearing at my skin. Was that another scream? Slow down. Breathe.
Breathe...
I lean my weight against a massive foreign tree and slow my pulse. All around massive trees sway in the stormy winds, allowing flighty permeation of moonbeams. The movement of the moonlight contrasts with a constant distant glow of an orange light beyond the tree I lean against. The wind picks up and I can hear the gentle chanting again. And smell blood.
Everything from that point forward was the play of the game letting us both (player and GM) be surprised by and collectively discover who the PC was and what the hell is going on here.
The scene on the bay? All we knew at that point was what had transpired up to that point:
* There were supernatural creatures/cults absconding with children from somewhere and a terrible ritual sacrifice.
* She saved these children from said sacrifice and learned a little bit about things; something terrible haunts this world...some kind of supernatural apocalypse (lycanthropy or something). The children were small enough that they didn't know where they were or where they were from. They were captured some time ago from varying villages that don't stray from their walls. A few were from a bay/river village (so she decided to find a river and follow it).
* Like The Road by Cormac McCarthy, all adults were proving dangerous or dangerously suspicious/protective (again, this turned into sort of a supernatural aftermath game as play wore on). Social interactions were fraught (at best).
* The physical world was violent and dangerous (benign topography as well as she was up in a precarious mountain domain with landslides and rushing rivers leading precipitously downward into a bay), with actual primal spirits, wicked fey, cults, and frightened humanoid communities besetting/accosting living things.
So she navigated several conflicts (including finding a place to safely stow these children while she journeys for help and to orient her to where she is and who she is). The rushing river hazard conflict ends and she filters out on the bay where the village is alleged to be.
The number of questions about this little girl and the father are endless. Who are they? Are they from the village that I'm looking for? Will they welcome me or rebuff me (particularly given the world). Does this sea creature haunt their fishing all the time? Is it some kind of creature that they worship and give offerings to so that their fisheries remain bountiful? The questions are endless.
But the player had intersecting longterm goals and the new scene opener crystalized her goals here and now. Save the daughter and father so that I can parley with them and hopefully they will help me/us (the children); either embrace me or reject me (depending on the success of the follow-on social conflict)...but I'll have more information regardless.
The number of ways that scene and the follow-on social conflict could have gone are myriad both in terms of the identities of the 4 parties involved (father, daughter, sea monster, village/villagers) and in terms of the trajectory of play.
Its an extremely odd thing to me to get hung up on "a stat block makes discovery/surprise impossible!" its not only not true...it seems a failure of...I don't know what? Conception of the giant creative matrix of realities in any given situation (particularly with so many unfixed parameters)?