Saw this post on Reddit about people passing on Minecraft maps. Basically one person plays it at a time and then saves it and gives it up for another person to take a turn. I thought it could be fun to try that with D&D modules. Rather than one person playing you start with a dungeon, have a DM run a party through it, record all the marks they leave and pass it on.
Now that I've written that, I remember people doing the same thing with Dwarf Fortress to hilarious results. (See the saga of Boatmurdered).
I know that an open-table megadungeon or Flailsnails campaign is already pretty close to this. But the DM's time and resources are still a bottleneck. With a Pass-it-On module, as long as there's a central location where it's hosted anyone could pick up the latest version and run with it. (I suppose there might be some technical difficulty with preventing simultaneous turn-taking or enforcing time limits).
It would be cool if each DM would submit a concise post-play summary when they re-post it. Not long narratives, but "party went left here, lost cleric to the trap" type affairs so there is a bit of context for the next DM to read up before running. You'd need to provide lists of the gear left on player corpses and explanations of non-standard magic item mechanics as well.
I wonder if this would quickly result in a wasteland devoid of life or treasure? Seems like tricks, or toy-like dungeon features that can't be moved or used up would work well. Maybe a slightly higher level would work so that parties coming in bring some of their own magic items and treasure, and some of them die leaving it behind. Maybe there could be 3-4 factions surrounding this area and players can never fully eradicate them just shift the balance enough that now one faction is ascendant, now the next.
Another thought that comes to me, is that both examples above involve building things so the map constantly has human-made additions. That might be more analogous to DMs collaboratively making a dungeon by adding chambers and features. But that doesn't seem as new an idea in D&D to me. I think I've heard of people doing that. But what if you could incorporate building into the dungeon by players?
Maybe a location on another plane or completely underground that requires work to secure food, safe lodging, or relatively safe travel from one area to another. Hmm, has anyone done much with building in dungeons by players? How long or difficult is it to block off an area with a brick wall, put in a sturdy door and lock, or build a bridge across a chasm? That might be shifting the game a bit from post-apocalyptic exploration to settling in at the old megadungeon, but could be interesting.