Definition: a room is neighboring if the number of moves from it to the location is 1.
Every turn:
if a random chance of 1 in 2 succeeds:
let current location be the location of the lurking critter;
let next location be a random room which is adjacent to the current location;
if the lurking critter is visible:
say "The critter [one of]slouches[or]slithers[or]shambles[or]lurches[at random] away.";
move the lurking critter to next location;
if the lurking critter is visible:
say "A critter [one of]oozes[or]staggers[or]ambles[or]creeps[at random] into the room.";
[Whether or not the critter has moved, we need to adjust the sword-glow, because the player may have moved.]
if the lurking critter is in the location:
adjust sword-glow to glowing brightly;
otherwise if the lurking critter is in a neighboring room:
adjust sword-glow to glowing faintly;
otherwise:
adjust sword-glow to glowless.
This snippet omits the definition of "the lurking critter" (a standard NPC) and the sword (a standard object with a custom defined method called "adjust sword-glow to"), but it should give you a good idea of what Inform 7 source code looks like. (Inform 6 looked much more like a traditional programming language).That must be a comment, right?
In that case: "The critter [one of]slouches[or]slithers[or]shambles[or]lurches[at random] away.";
[one of] [or] [at random] are also comments?
Also https://sharpee.net/
Arguably, the right answer now is to document everything that matters to you about the adventure, and tell an LLM to run it.
It would write the book ahead of you, kind of like how railroads could send trains with supplies out to the track as it was built.
It also allows you to deviate from the novel. This is a romance novel. I had the main character choose someone else and it showed an alternate version of the novel. After the main threat of the story was dispatched things settled into weeks of routine living where I added another person into my routine. I played to see if another event would show up but after 3 in game weeks I decided to stop. This was a test and I needed to improve the game. I can see this becoming addictive to some people because they will be living in the story and having a life there and making friends and finding partners.
This type of game is still uncharted territory. Does one end the game or let the player play indefinitely? Is it more fun to have the player do the daily life things or skip those or give them a choice?