Just some numbers for my GURPS Dungeon Fantasy megadungeon game, exploring the ruins of Felltower.
My megadungeon, in 11 numbers:
3 - deepest level plumbed so far
4 - total number of PCs killed
5 - deepest level heard of by the PCs.
6 - different levels or sub-levels visited (even if only briefly), including the surface ruins.
16 - total number of allied NPCs (hirelings, henchmen, recruited monsters) killed exploring Felltower
17 - sessions in the books (25 total, but only 17 in the megadungeon)
45 - approximate number of different kinds of monsters encountered (by race or species)
75 - approximate number of encounter areas explored on level 1
75 - approximate number of encounter areas explored on level 2
79 - number of different rumors heard
180 - approximate number of encounter areas explored overall across all levels visited.
Number of monsters slain and amount of loot retrieved? It was too hard to count, but plenty of monsters have been put down and enough loot has been garnered to keep them coming back.