Hi, I have made various games in a jam setting (two of which can be found on my itch page). I just wanted to post some general advice for those who are looking to jam a narrative game for this jam. Note that this advice is not universal, mileage may vary, but I feel it would be a good place to start. Furthermore, if you want to add to this, feel free to respond to this thread as well with your own advice even and especially if it might contradict my own.

• Keep it under 5000 words max. I even only suggest this high of a word count because we have two weeks. For the last two Global Game Jams I wrote roughly 1500 words each including code, and that was in 48 hours. 
• Figure out the mechanics/hook first, then write the narrative to emphasize the mechanic. Try and build a small prototype/proof of concept of that mechanic, then expand from there.
• I would also recommend a rough outline that has all your important nouns, verbs, and characters. 
• Further, if you are doing a choice based IF, I would recommend including in your outline an emphasis on your major choices where the narrative branches. If a parser game or walking simulator is more your speed, a section in the outline giving a quick rundown of your rooms and their interactable objects would also be a good idea. 
• I would also make  a rough outline of the plot as well, something akin to doing a basic story circle as popularized by Dan Harmon. Organizing these will give you much more structure in building your game and give you a roadmap to build, plus its experience towards Game Design Documents.

More advice can be found in the NarraScope discord's Game Jam channel, so I would recommend looking through that as well. So good luck on getting a game made, I believe in you!