Stuff to Include from Dungeon Crawl: Stone Soup

Put these here to divide areas via environmental hazards, or to protect treasures.  Could also use acid, electricity, poison clouds, lava, etc.

Characters that die in the megadungeon or other areas may show up as “ghosts” that try to take revenge or otherwise kill the characters.  Maybe they focus on the character of the player?

Once killed, the ghost is gone forever, but they never drop loot.

As a corollary… graveyards!  Mysterious graveyards and mausoleums in the dungeon that have names of past adventurers and explorers…

It gives the ability to see other areas without actually being able to get to them right away.

For example, here’s a common example of what happens in DCSS, a room that is only accessible by stairs from the lower level:

Perhaps these are great columns?  Might be fun… what’s in that water?