Last night I took a few minutes and got some work done on Felltower.
I culled out the rumors heard from the rumor list, and then added back in a few to fill the list back out. I didn't finish the job but I got in a few. That's pretty normal. Also, I did my usual re-numbering - my Word auto-list will sort the old rumors down as I cut out the ones heard, so I add new ones randomly around in the list so "30" isn't the newest and "1" the oldest. They move around as I edit.
The point here is that I browsed the rumors, and looked at some old rumors that finally connected to game events. These are basically "spent" rumors, although they could have connections and repercussions in the game ahead.
"There is an immortal elven swordsman under Felltower who kills everyone he meets. Some kind of curse trapped him there."
That one came up fairly recently, although it was on the table for a long time before that. Valmar was encountered and slain. The curse wasn't explained, although the origins of sword-spirits are known to the PCs so it doesn't necessarily have more depth than that.
"I heard from this drunk wizard that if use too much magic on stones, they can wake up and turn into rock monsters."
Ask Dryst about that. He wasn't even drunk when he birthed a gargoyle.
"There is some kind of bogey-man near the mountain - it’s killed a few hunters in the past couple years, choking them dead and eating their guts out."
A bugbear kind of bogey-man, even.
"That big dragon used to fly around from the north side of the mountain, so maybe it lives up there."
That turned out to be true, too - there is a big dragon in a cave that sits on the north side of Felltower.
"There is supposed to be some demon-god that walks around under the mountain, killing everything it sees."
That's the Durak, the Lord of Spite, right there in the rumors from session one.
There are more, of course, but some of them make me chuckle when I see them again - how early, how blatantly or how back-handedly, and/or how accurately rumors pegged something to come.
I won't even really go into the dozen-plus rumors that said you need a six-fingered hand to open doors, not all keys are physical keys, it's the hand not the key that opens doors, etc. etc. that were sprinkled in there. Turns out, they were all true in spirit and often in literal text.
But even when the players don't make the direct connection, it provides a good base of knowledge - when they first met the Lord of Spite, no one was shocked that there was this blue ogre stomping around hitting people. When the stone they'd shaped was all gone, and coincidentally there were more gargoyles, that made sense later when Dryst really blew a roll. And so on - sometimes it's a rumor, sometimes it's foreshadowing, sometimes it's a red herring . . . but it's all bite-sized backstory so you don't need to read a block of homework text just to play the game.
Restocking can be a chore. Not always, though. I enjoy going through areas the PCs partly bumped into and seeing what's there now - use strikethrough text on X gnolls and replace it with X-Y gnolls, buff up A into A + B as reinforcements come in, move C from room 22 into room 45 as it's moved to a less threatened area, etc.
But I got some done, and although it's weeks until the next game of Felltower it's ready to play in right now.
I'm a big believer in the "never erase, just draw more" style of megadungeon mapping. Put something down on paper and keep putting stuff down, don't keep stopping to make it perfect. It's a philosophy I carry into a lot of things - "let's get it good enough to try, and then try it" instead of "get it so it's perfect, then try it." Don't let the perfect be the enemy of the good (enough).
All that said, I have fixed a few things on my maps. Connections that looked good on my map but which were very difficult to describe, sometimes even impossible given vocabulary disconnect.
I've made a few modifications to fix that. I cut off a corner here or there on rooms that served no purpose. I've taken a few twists out of corridors that equally did little, especially if they visually clashed with the layout on my own maps in a way that made me say, "Why was that done?"
I added in a few twists and turns, though, which better explained what the stocking rolls told me the areas are for. This is a barracks and lacks a nearby pit for waste? Add one, if it makes sense, or turn an "empty" room into a waste room. This is a guarded area but there are no places for guards? Note where they are, and figure out what what changes would make guarding it make sense (like, adding a niche for a guard post.)
It's nibbling at the edges, really, and didn't need doing, but it was in areas not yet explored by the PCs and where actual play called for making it easier to actually play.