grodog said:
That's one of the things I've appreciated most about Necromancer Games' Tomb of Abysthor and Rappan Athuk serieses: in the intros, Clark and Bill comment that one of the main drivers for play in a dungeon is to provide the players with goals. Players don't willingly enter RA, they are sent there to retrive X from evil temple Y on level Z; or the PCs must secure the services of alien wizard A on level B in order to accomplish unrelated-to-this-present-dungeon-environment goal C; etc. In OP map play, the players' piecemeal exploration of the map over several expeditions would likely provide those kinds of tactical goals directly.
Allan's observation about Necromancer's dungeons is spot on, and highlight a difference between "archetypal" 1st edition AD&D and Original D&D dungeons. In the former case, much more attention seems to be given to populating the whole complex, and sort of "compressing it" to focus on the "meat", so to speak. TSR's modules tend to emphasise this style*, I guess primarily for considerations of available space and company resources. Necromancer's Rappan Athuk and Tomb of Abysthor and the (freely available) Mines of Khunmar by Stefan Poag all embody the 1st edition approach.
In the OD&D case, as T.Foster pointed out, the dungeon can be
the game (although as Judges Guild's early products demonstrate, the same philosophy can be applied to wilderness and city adventures); there is no overarching objective apart from having fun in a dungeon-type environment.
As a personal note, I always wanted to do an OD&D style megadungeon, but the lack of time, creative energy and attention span means the AD&D approach works better for me in practice. When I was a teenager, I sort of approached the large megadungeon campaign with the first Ruins of Undermountain set by using the maps only and making up rooms and encounters on the fly, but I don't believe I will ever do a "real" megadungeon on my own. I will probably buy and run Castle Zagyg or Blackmoor Castle when/if they come out.
___________
* D1: Descent into the Depths of the Earth may be an exception, although it is a tricky case... it may be thought of as a dungeon, but also as an "underground wilderness".