The New Dungeon lengthening
Wow, I was just looking at this game again the other day, too funny.

While I haven't played in a few years, I do remember our group has used one (or both) of he following rules to make things play longer:


Increase by 50% or 100% (depending on how long you want the game to play) the amount of loot necessary to win the game.
Require that in addition to collecting enough loot, you must have collected at least one piece of treasure from each floor, or from a specified number of floors.