A story that you're currently writing can go anywhere you want. Literally.
For the moment, let us consider tactical play. The party walks into a room. There's an ogre sitting on a chest, from which spill gold coins and jewels. The ogre is playing dice with four orcs, sees the party enter, stands up, grabs his giant iron maul, and says to his companions, "Hey, guys, looks like some tasty-human meat just walked in. Let's eat!" The GM says, "Roll initiative."
There are nearly an infinite number of things Flexor The Mighty could do in this situation. He could sit down on the floor and twiddle his thumbs. He could start reciting a soliloquy from Hamlet in Elvish. Or, he could bring out his +3 Axe of Ogre slaying. All of these are
valid actions within the rules. Only one of them is likely to be tactically sound play.
Taking out that axe and charging into melee is a valid play, and tactically sound. But it might be even
better if Flexor waited two beats, so that his companion, Whizbang the Magnificent, could get an area of effect spell off on the enemy before Flexor made placing a fireball difficult by getting into melee with the ogre.
So, with the
assumption of tactical play, there's an
assumption that you're expecting to take on the tactical challenges. Given that, there's a great many choices that are technically valid, but nonsense in context, some that are decent choices, and some that may be awesome choices. You will never know what the
absolute best choice would be. You only have relative measures between things you can think of in the moment, and your vague expectations of the future.
What you seem to be missing is that there's similar assumptions for story-oriented play!
If you are engaging in story-focused play there's an assumption that you're trying to make a
coherent, interesting, and entertaining story out of the bits you have. Similar to the tactical scenario - of that vast infinite of story choices that are valid, whole swaths of them are nonsense that would turn your story into
Calvinball: The Novella. Funny for about four seconds, but then it flounders into babbling. Some other choices will be decent, and some will turn out to be awesome.
There are no rules, not even the suggestion of rules
Oh, sure there are rules. Go to your local library. Section 801-809, as enumerated in the Dewey Decimal System includes literary critique and criticism. There's tons of stuff there about what makes for good and bad storytelling!
You have limited bits - a genre choice that lays down expectations of what's a valid approach to story. You have a number of characters, each with their own fictional positioning. The
game rules lay out things you can and cannot do to manipulate the story.
Miss Marple, when she has all the suspects in the room and is about to announce whodunit, is not going to whip out a laser sword and announce, "Aliens did it! ATTACK!" even if the rules allow it, because that's a frelling stupid way to end an Agatha Christie mystery.
because that would be formulaic writing, and truly formulaic writing is almost always bad.
Well, there you go! There's a rule: "Don't be formulaic."
I could continue, but I think these are the constructive bits for the moment.