The Mega Dungeon Conundrum

I was thinking last night, rather than sleeping (which seems to be the case on Sunday nights for me).

What constitutes a mega dungeon as far as the amount of rooms?

Is there such a yard stick to measure this?

I'm slowly starting to get back in the correct frame of mind to finish my damned dungeon.  As it stands I believe I had 11 maps x 18 rooms a pop.  Which would be somewhere in the neighborhood of 198 rooms maybe.  There were a few underground cities that had less rooms (houses).

Obviously "Maze Of The Blue Medusa" has set the bar ridiculously high as far as room count goes.  I believe it clocks in at 300.  Which honestly makes my brain hurt.  For the simple sake that I was having trouble with 198 rooms.

Castle Triskelion (which can be found daily at http://castletriskelion.blogspot.ca/ ) I'm guessing is way over a couple of hundred rooms.  They are on level 5 on the blog, and the downloads for level 2 are up to 78 rooms.  http://www.and-mag.com/castle-triskelion-inner-ward-second-floor-published/

Granted both of the above projects I figure are/were/started out as a "labour of love" I think.  It is still quite amazing!

Anyway the usual bit of rambling from the proprietor.

What constitutes a mega dungeon as far as the amount of rooms?