My 2021 NaNoGenMo entry is a choose-your-own-adventure version of Herman Melville's Moby-Dick.

The original text is broken into sections, which are then reconnected with decision links. Each decision point is created by recasting a sentence from later in the text, from the section that it points to: broadly speaking, it searches for a first-person or second-person fragment that include a past-tense verb, and converts that into a present-tense option: "I duly arrived in New Bedford." becomes "To arrive in New Bedford, turn to page X."

Example output: https://kevan.org/nanogenmo/2021

The text of the linked draft is 247,354 words.

Example entry:

25

I sat down on the side of the bed, and commenced thinking about this head-peddling harpooneer, and his door mat. After thinking some time on the bed-side, I got up and took off my monkey jacket, and then stood in the middle of the room thinking. I then took off my coat, and thought a little more in my shirt sleeves. But beginning to feel very cold now, half undressed as I was, and remembering what the landlord said about the harpooneer's not coming home at all that night, it being so very late, I made no more ado, but jumped out of my pantaloons and boots, and then blowing out the light tumbled into bed, and commended myself to the care of heaven.

Whether that mattress was stuffed with corn-cobs or broken crockery, there is no telling, but I rolled about a good deal, and could not sleep for a long time. At last I slid off into a light doze, and had pretty nearly made a good offing towards the land of Nod, when I heard a heavy footfall in the passage, and saw a glimmer of light come into the room from under the door.

• To lie perfectly still, and resolve not to say a word till spoken to, turn to page 36.
• To find more patrician-like houses, turn to page 41.
• To lie there, frozen with the most awful fears, not daring to drag away your hand, turn to page 40.
• To sally out for a stroll, turn to page 50.