Dungeons don't need doors for every single doorway. Doors exist basically to control access, and if there was no reason to control movement between two areas, you wouldn't put a door there. This is why the simple d6 roll I proposed last time had half the results be open doorways rather than doors, although we could certainly adjust the probabilities.
Most doors are built to do one of the following:
- Block or Contain (keep something in an area)
- Defend (keep something out of an area)
- Isolate (keep distractions out of an area)
- Prevent Observation (keep events in an area private)
All of these have real-world examples: cell doors, security gates, bedroom doors (which isolate sleepers from sounds and provide privacy,) meeting room doors (which keep discussions private.) We could also add Restrict or Redirect Traffic: sometimes a door is not about preventing access, but keeping the number of people down to manageable levels. In the dungeon, the most common form of "redirection" is "downwards redirection" via a trap door, but you can also have one-way doors, doors that open for a brief moment then snap shut, in addition to small doors that simply prevent more than one person entering at a time.
We also have doors that aren't strictly necessary, or that exist in forms that aren't completely necessary: they maintain an environment (fridge door keeps contents cool,) hide an unsightly mess (closet door,) or serve a symbolic function, like super-huge bronze doors on a temple or courthouse that remain open all the time, but look impressive. Environmental control doors can be considered relatives of Isolating or Private (Preventative) Doors, but we could combine the other two into Virtual Doors, doors which aren't meant to control access, but opinion.
For dungeons or supervillain hideouts, you also have Fake Doors, which lead no where and serve only to confuse, and Secret Doors, which allow unseen access. Hidden Doors are not the same as Secret Doors, because they are built as ordinary doors, then covered up; who hid the doors and why is an important question to answer.
This all suggests the following d12 replacement for the d6 roll for door types:
- Blocking/Containing Door (R/O)
- Defensive Door (O)
- Isolating Door (E)
- Fake Door (R)
- Virtual Door (R)
- Secret Door (R)
- Preventative/Privacy Door (E)
- Hidden Door (R)
- Non-Door (R)
- Redirecting Door (R)
- Broken Door (R)
- Empty Doorway (-)
The letter codes in parentheses after the door type indicate some other information we need to roll for:
- (R)eaction: use the standard reaction roll to determine how the door's architects (or concealers, sealers or breakers) felt about what's behind the door, or who's using or viewing it. For Secret Doors, the roll determines on which side of the door the person using it would rather be.
- (O)bject: use any roll you feel is appropriate to determine what is being kept outside/inside of the area behind the door.
- (E)vent: use any roll you feel is appropriate to determine what condition or stimulus the door is meant to control.
I'm sure I'll be revisiting this later.