Okay but this allows me to corner you in my concepts of What a DUNGEON is-
A dungeon is a sort of perpetually expanding space and in itself is it's own type of BIOME. Consider.
Where are you going to store your extra magic items when you run out of room in the armory? Or ones that are broken and need repair? Or just don't WORK as good as they used to? The Guest Bathroom? No, IN THE BASEMENT/DUNGEON. With the Christmas Decorations.
Over time, magic seeps from these artifacts and imbues the surrounding closed off area (i.e. A basement/dungeon) with properties. Magic tends to attract creatures like Goblins. Goblins are the FIRST sign a dungeon is starting-they'll take up residence in a preestablished spot that is assured to be safe and they'll begin working on expanding it along with the magic that naturally expands it-so their families have room to grow as well as making rabbit warren like mazes to confuse intruders. Over time, the area grows bigger and bigger and more creatures begin to move in. Tentacle Beasts, Mimics, Displacers, etc. And then undead will start occuring as these predators begin to drag in dead bodies and leave the remains laying around. Then with outside elements now coming in like water, blood, miasma, etc.-Slimes begin to form. And Wowiee WOW! You got yourself a nice proper DUNGEON!
Some people take advantage of these places, like Liches, Irate Wizards pissed off with 'The MAN', rouge and mauraders looking to store their loot in an assured safe house or even Dragons seeking a place to put their fat asses for a hot minute. Sometimes a Dungeon being full of gold is just a result of Goblins collecting things and leaving what they don't want around. (Sure this Gold piece is worth more, but this COPPER PIECE is a 1459 MINT Queen Arthesiandra INVERSION so it's UPSIDE DOWN. Much much cooler.) or Liches/Wizards throwing their trash on the ground.
As The Dungeon becomes a Biome, it develops it's own flora to correspond with fauna; mostly mushrooms, plants that grow well in limited to no light, etc. etc. Lichen is a BIG part of dungeon dweller diets to the point of it being a part of agriculture. As well as unusually large blind insects that dwell down there (think Cave Crickets the size of CATS)
Dungeons are the most fascinating thing that could potentially exist because it can be ANYWHERE. Which is why Peasant NPC #98 is really concerned about the fact there are REALLY big rats in his Storage Cellar because that is possibly a DUNGEON IN PROGRESS cause he left his great Grandma's broken flying broom down there with the intent on fixing it one day.
