At GenCon 2007 I received a refresher course on one-way
doors while co-DMing the Bottle City
level of Castle Greyhawk with Rob
Kuntz. This was my first play experience
using one-way doors in at least 15 years, and Rob’s take on them was quite a
bit different from how I had always pictured them in my head. In Rob’s view, one-way doors acted as normal
doors from the “door side” and once the PCs passed through them, the door
closed (automatically if not spiked), and was gone. From the “wall side” the one-way door was
detectable as a secret door, but even then could not be opened with a knock spell. I had always pictured one-way doors as doors visible
from both sides, but only being openable from the one-way side---the other side
appeared as a normal door that could not be opened (I may have unconsciously
been following the lead of Roger Musson’s “Dungeon Architect” comments on
one-way doors here). I like Rob’s
version better, for reasons that’ll become clear soon.
On the Bottle City
map, Rob used the now-standard false door symbol to represent one-way
doors. This shared symbol appears in the
sample dungeon map in Underworld &
Wilderness Adventures on page 4, and denotes a false door on that map. The now-standard false door symbol is also
used as the one-way door symbol in the 1978 monochrome editions of G3 Hall of the Fire Giant King and S1 Tomb of Horrors, and the S1 usage of the symbol is easy to
confuse with a false door (a problem even more evident in the 1975 Origins tournament version of Tomb of Horrors). The symbol
for one-way doors standardizes in 1981’s Moldvay
Basic rulebook, also used for the 1981 green-cover edition of S1.
One-way doors are specifically mentioned in OD&D: “Doors which are openable
from one side only” (U&WA, page
6) and “Doors which will open to allow
traffic into an area but not out of it” (Greyhawk:
Supplement I, page 61). Appendices G
and H of the Dungeon Masters Guide also
list “door, one way” and doors and stairwells as sample trap- and trick
examples and building blocks (pages 216-217).
I like Kuntz’s definition of a one-way door---any door that
appears like a normal door from one side, but is a wall from the wrong side,
with no physical hint that a door exists on the other side. One-way doors reinforce the utility of iron
spikes as standard equipment for PCs, and (if detectable) also provide DMs with
leverage against players who constantly search for secret doors---PCs may
discover the wrong side of a one-way door, with no way to open it from that side,
which will waste time and generate more wandering monsters while they futilely
roll d6s….
One-way doors can be placed as standard one-way doors or as
one-way secret doors, and other dungeon features can easily be defined as
one-way corridors, stairwells, chutes, covered pits, etc.
Variable Stairs*
One-way doors are the most-basic element of what I think of
as a suite of related dungeon features which limit and/or channel PC
movement. Variable stairs are a great example of “upping
the ante” from one-way doors, but unlike one-way doors, variable stairs are
only hinted at in OD&D. Page 6 of Underworld & Wilderness Adventures mentions:
- Steps which lead to a slanting
passage, so the player may actually stay on the same level, descend two levels,
or ascend two levels
- Trap steps which lead up a short
distance, but then go downwards for at least two levels, with the return
passage blocked by bars or a one-way door
- Doors which are openable from one
side only, which resist opening from one side, or which appear at random
intervals
Variable features behave with more uncertainty than
reliable, though tricky, dungeon features like one-way doors: the variable stair can lead up or down, and
while it is still trustworthily predictable, the PCs don’t know that, of
course---to them the stairs appear very unpredictable, and their maps will be
befuddled. While the change in the state
of a variable stairwell from up to down is obvious, it has some subtle
implications. How often does the
stairwell change? What triggers the
change? Can the change be specifically
invoked to shift the stair to the direction the PCs desire, and if so, how? What does the stair look like from the
other/up side, when the stairwell is currently going down (and vice-versa, of
course)? The answers to these questions
lead to a variety of adventure possibilities for a DM, and potential headaches
(and challenges, and perhaps rewards) for the players.
The key to take away from the U&WA suggestions above, and the idea of variable stairs in
general, is uncertainty: after exploring a dungeon level for awhile,
PCs shouldn’t necessarily know with surety that they are still on the same
level, and they shouldn’t necessarily be able to rely on their return route
being the same as they attempt to exit the dungeon, even if they’ve mapped
correctly. Variable stairs help to drive
that uncertainty, in two stages of features:
predictable and unstable.
One of they key differentiators between one-way- and variable
dungeon features is their reliability.
That is, a one-way door behaves the same way each time you encounter
it: the door cannot be opened from the
wrong side, but when it is opened, it always opens into the same hallway or
room (although the PCs cannot return to their original location by simply
reversing their direction of travel). Predictable variable stairs (or other variable
features) may lead to different places when encountered at different
times: when first found, variable stair
A leads down; when passed on the way back out, stair A leads up instead of
down. That is, stairwell A leads down to
level 2 or up to sub-level 1a, but within the scope of those two constraints,
stair A behaves otherwise itself. It is predictable, though variable. Now, if the DM changes the frequency of stair
A’s options, it become a bit more uncertain, and a bit more dangerous: if stair A leads down to level 2 5 times in
6, and up to sub-level 1a 1 time in 6, that’s going to make level 1a much
harder to access (and potentially to leave when the time is right). It’s also going to make sub-level 1a a place
that the PCs can be stranded within, that will require them to pack plenty of
iron rations in case the stairwell gods are not with them when they’re trying
to leave (or enter) that sub-level….
The second stage of uncertainly for variable stairs is unstable, which is simply a push beyond
predictable variation into unpredictable variation. Variable stairs are variable because they lead
to different (though fixed and binary) destinations. By opening up the destination possibilities
for variable stairs, trap doors, hallways, pits, etc., the DM starts to play in
the realm of unstable variable stairs
(or other dungeon features): these lead
to multiple potential destinations rather than the simple binary options that
an up/down stair suggests. For example,
variable stairway B on level 4 key #62 leads:
d12
Roll |
|
Result |
| 1 |
|
Down to level 5 key #4 |
| 2-3 |
|
Down to level 6 key #14 |
| 4-6 |
|
Down to level 7 key #24 |
| 7-9 |
|
Down to level 7 key #44 |
| 10-11 |
|
Down to level 8 key #34 |
| 12 |
|
Up to level 4c key #12 |
Clearly, stairway B is not nearly as predictable as
stairwell A. And we’re not done
yet! What if stair B also disappears
completely after it is traversed, and doesn’t reappear for 1-6 turns, or hours,
or even days!? If the feature is gone,
is another area revealed in its absence---that is, with stairwell B not present
at all in key #62, is a door (perhaps one-way?) into key #63 now visible that
would otherwise be inaccessible while the stairs were present? Worse, what if stair B behaves differently
upon ascent vs. descent: the PC will
have fought their way through a level 8 encounter, and decided to beat a hasty
retreat back to level 4, only to find that stair B now leads elsewhere upon
ascent (and perhaps even “ascends” into a deeper level from below!). The possibilities and combinations are
practically limitless!
The Accessibility of Dungeon Sub-Levels
Sub-levels are generally thought of as more-remote areas
that are offset from the main dungeon’s levels; classic examples include the
three levels of WG5 Mordenkainen’s
Fantastic Adventure (sub-levels to the main Maure Castle/Castle El Raja Key complex), and the Interdicted
Prison of Zuggtmoy and the Elemental Nodes sub-levels in T1-4 The Temple of Elemental Evil.
However, using one-way and variable dungeon features, DMs can insert new
levels into old, well-trodden paths, by changing an existing door or stair into
a variable one.
This new sub-level is territory added to the known and
explored regions of the level, but is accessible through a newly-changed
dungeon feature (or the newly-discovered property of a rarely-varying feature,
if the stair only leads up 1 time in 20, for example). PCs could learn of the new sub-level’s
existence by hearing rumors at the local alehouse, or through finding a map
that disagrees with their own, or observing the feature behave differently when
employed by monsters or an NPC party, or from legends that “The Fox’s Hole” is
only accessible from the SE stair when the moon is full. Regardless of the method, by employing
one-way doors, variable stairs, and the other sundry dungeon feature
combinations, DMs can easily insert new levels or sub-levels to expand existing
territory beyond the map’s edge, or even to overlap new and existing territory
within a level. That is, with a variable
door, an entirely different map may exist beyond the door, a level with
features that would conflict with the previously-known level map.
If the new sub-level is self-contained and only accessible
from the variable feature, then living creatures will probably be less common
on the level unless it has a food supply and/or its inhabitants can create food
and water (or don’t require such, like golems, undead, etc.). Any sub-level isolated by a 1 in 8 or greater
chance of not being found becomes a very appropriate challenge for higher-level
adventurers, and presumably for placement in the lower dungeon levels. However, don’t discount the possibility of
making such rare sub-levels accessible from one of the upper levels of the
dungeon complex, too, since any group of explorers (lower-level or
higher-level) are less-likely to find the Hideous Sub-Level of Doom in the
first place. To introduce this concept
of variable stairs providing access to sub-levels, a DM should insert some
examples that will teach players the ropes of such features: perhaps some of the sub-levels have multiple
means of ingress and egress, and perhaps the variable features are strictly binary,
or if they disappear completely they’re only gone 1 time in 2 to 1 time in
4. Springing such features on players
with no experience with this kind of trick can be very frustrating, so building
up their confidence by setting expectations with background information
in-character, as well as an initially–forgiving play experiences will allow a
DM freer reign to turn the heat up on such challenges as the PCs and players
grow more experienced.
In addition to their utility for managing access to
sub-levels or to new levels added within a well-known and explored level,
one-way doors and variable stairs provide an additional level of variety and
challenge within the campaign dungeon environment. These trick features force players to stay on
their toes and also reward careful player mapping---and mapping is perhaps the
best way to defeat these devices (along with knock, dimension door,
and passwall, of course!). A word of warning though: one-way doors are easily susceptible to abuse
as channeling devices if over used. The
occasional series of one-way doors that herd PCs toward some special encounter
or to a stairwell down four levels is OK, but if one-way doors always force
players into yet-another Kobayashi Maru or Catch-22, the features will quickly
lose their charm.
I tend to think of one-way doors primarily as trick
encounters but they can also act as channeling traps too by forcing PCs into
environments that they would not have otherwise explored, or by trapping them
in an environment that would not otherwise have willingly chosen to enter,
without a known path of return. Variable
doors and stairs are potentially much more dangerous, since they force PCs to
wait for the feature to return or reopen (which may take hours or days!), or to
explore further in the hope of finding egress and a return to known paths. If the variable feature opens into a
sub-level, however, it’s entirely possible that the feature itself may be the
only means of entrance (and exit!) to that sub-level….
One-way doors and variable stairs can help hidden sub-levels
to remain hard to find, and hard to return from, and keep your players on their
toes as they wonder whether the stairwell that they used to access the Hidden
Crypts of Boccob will still be there when they are ready to return to sunlight,
fair maidens, and fine ale. I hope
you’ll enjoy adding them to your campaign dungeons!
Happy Delving!
Allan.
* I haven’t been able to track down the exact origin for
variable stairs as I’ve described them; I’m pretty sure that I read about them
somewhere, but it’s possible that I just combined the U&WA descriptions of the trick stairs and added my own
twists. If you find a definitive source,
please let me know!
"One-Way Doors, Variable Stairs, and the Accessibility of Sub-Levels" first appeared in Knockspell Magazine #1 (Winter 2009). This version of the article includes the errata published in FKQ#2 that expands and corrects the second paragraph.
