Some Trap Theory

The point of this whole exercise is to find ways to categorize traps and puzzles and tricks.

Why?

First, it might help DMs think of new ones. Or new ways to use old ones.

Second, because when you have random tables of traps, sometimes half the ones on there are useless to you since they don't match what you're trying to do in the dungeon--so creating categories is a way to make more "targeted" tables and tools.

Like: if you're designing the grimdark viking raider hideout, maybe you don't want to have a trap that blows up anyone who touches it like a balloon.

I'm going to use the word "traps" in this thing, but it's actually usually a shorthand for "traps or puzzles or other similar nonmonster dungeon features" because saying "Traps" is faster.

So, basically there are 4 ways of categorizing traps I'm looking at here:

1. Testable traps or untestable traps
2. Clued and clueless traps
3. Reason the villain made the trap the way it is
4. Reason the DM made the trap the way it is

There are a million other ways to categorize traps and puzzles ( "with monsters/without monsters" etc) but I'm concentrating here on categories that are less obvious but equally helpful to consider during the brainstorming/design process.

Testable v. Untestable
"Testable" simply means that PCs might have a way to find out what the thing does without automatically falling prey to that effect--whatever it might be.

An ordinary tripwire-and-poisoned-dart trap is testable. A long corridor leading to a room that can only be reached via that same corridor that is cloaked in impenetrable silence and darkness and that deadens the senses of anyone in it and eats any elves that pass through it is untestable. A puzzle that spits out a given prize or punishment the first time (and only the first time) you respond to it in a certain way is likewise untestable.

It's an important distinction. The tests PCs devise to examine testable features are a big part of the fun of those traps--often more important than what the trap actually does. There's a reason there's all that damn livestock in the AD&D equipment list.

Non-testable features are harder to make interesting. The thing happens once and the PCs don't discuss it or strategize about it. One way to make them interesting is to give clues as to what might be coming up (see below) and let the PCs imaginations run wild.

The way you DM can also mean the difference between a testable and non-testable trap. Like let's say you've got a doorknob that makes you wink out of existence if you touch it:
-PC throws a rock at it
-You say "It disappears forever"
Well that was testable.
But if:
-PC throws a rock at it
-You say "It vanishes"
then suddenly it's not testable since the PCs don't know if it's disintegrated or just teleported somewhere else.

Anyway point is: almost every single kind of trap below comes in testable and non-testable versions.

Clued V. Clueless
Clued traps give perceptive PCs a hint that there's going to be a trap. More importantly, clues can give a clue to the skill/resource that is being tested by the trap.

Clueless traps are tough. Clueless and untestable traps are a hallmark of the true Deathtrap Dungeon. The only way to survive a place with tons of clueless and untestable traps is to run through it, die, and come back smarter the next time. Luckily, these are few and far between. Even the Tomb of Horrors had some testable traps.

Why Did The Villain Make The Trap Like That?
This is an attempt to define all possible in-game rationales for traps/tricks/puzzles. i.e. Why did the dungeon's designer put the trap there? Knowing this makes it much easier to design traps...(If you think I missed one, hook us up in the comments):

Regular Traps
These are there to prevent people like the PCs from doing what they're doing. (Get where they want to go, steal what they want to steal, etc.). Generally these will be designed to: (in approximate order of level of technical sophistication of designer)

-set off an alarm (lowest tech--easiest to make)
-allow inhabitants to attack PCs from a position of safety (i.e. corridor full of arrow slits)
-capture the PCs mechanically
-kill the PCs mechanically, or
-cripple the PCs mechanically and then allow for their capture (highest tech--hardest to make)

Regular traps basically work and the only way to circumvent them is, generally, to approach them in some way the designers did not intend or with some resource they didn't expect. Like if you're so shockingly strong you can hold the spiked ceiling up, or you've got a potion that allows you to move right through the portcullis, or you brought a battering ram.

Note that "regular traps" can include magic traps, too, so long as they were designed the same way: get the most bang for your buck out of the magic available.

Point is: there should be no way out of these traps without bringing something clever or extra to the table. They were designed by rational minds with the right tools. There's no good reason they wouldn't do what they're supposed to.

These traps are actually surprisingly unusual in actual modules. Usually the only way to design an effective, interesting adventure that includes ordinary traps is if they're clued.

Flawed Traps

These are intended to work like Ordinary Traps but PCs do have some fairly clear means of escaping/avoiding them. (Like for example: if, on a succesfful dex roll, 50% of people would escape a given trap, that's likely a flawed trap). The usual reasons include:

-the tech level of the designers is low
-the trap is old and/or broken
-the trap is already sprung or partially sprung
-the trap was hastily improvised recently
-the trap was intended to catch someone or something unlike the PCs

These traps are probably the easiest to work into a typical dungeon. The PCs have a reasonable chance to escape and reasons the traps might be there are plentiful.

Smart PCs and smart DMs might be able to map out what's going on in a dungeon simply by examining the flawed traps they come across and figuring out why they're flawed.

Mischievious/Insane Traps

This is the funhouse-style or cray-wizard-style trap or feature. The trap has no clear purpose other than, possibly, to entertain someone who made it. They might kill you, they might make your ears grow. For DMs, these are fun and easy to design.. Only thing you need to do is to think up some lunatic who put them there.

Sidenote: these are almost always magical, so the area of entirely mechanical traps that are still just there to fuck with you is relatively underexplored territory. At least in published books.

Worthiness Tests

These are traps that are designed to test who is worthy to enter a place or get a thing. They're nice for the DM since they dovetail well with the DM's out-of-game goal of testing the PCs anyway. The hard part is less designing the traps themselves than figuring out scenarios where some entity would want to use automatic devices to test people. Once you know what's being tested and who the designers were, making the actual traps isn't that hard.

(Related, but slightly different...)
Educational Traps
Sethor said...

I'm not sure if this fits but I've used traps I would classify as tests of education. These could fit into several categories but the intent of the trap builder was to educate those caught by it. A classic example would be a thieves gauntlet which refines the skills of their guild members. It does harm, but only enough harm to make sure they remember it.

Or alternatively these tests of education might result in something highly annoying. My favorite was the sticky doorknob that injected a needle, drew blood, enchanted said blood with continual light and then reinjected it. Voila, lightly glowing thief. Obviously someone with the capability to accomplish such an elaborate trap could simply execute the person but this performs a different goal.

A great number of ritual and worthiness traps might fall under this concept, particularly right of passage or graduation tests.

Ritual Traps

The designers have some arcane ritual and the traps (or puzzles or whatever) are part of it. These are essentially very similar in design specs to "mischievious/insane" though if the DM has the time to think about the religion or culture they came from s/he can make them a little more internally consistent. Perhaps consistent enough that the PCs can understand and anticipate them.

"Spider" Traps

These are traps which--like spider webs--are set by animal-intelligence beasties to catch prey and then eat it. Other than being organic, they function just like Flawed Traps.

Curses

We all know what a curse is. The important thing to remember in this context is a cursed place or item basically doesn't have to make that much sense or actually be effective in preventing PCs from getting to places, it just has to be inconvenient. Curses aren't so much about security as revenge.

Staged Sorting Traps

These can be combined with ritual or testing traps or can be their own thing. The idea here is the traps are designed not just to fuck with people, but to separate them according to the kind of person they are or by how they react to the trap.

For example: a magnet trap that sends anyone wearing plate or chain mail one way and those wearing no metal another way. The key here is more stuff has to happen after the sorting--different things happen to the different groups.

Like those old Fantastic Four Comics where the Human Torch would get separated from everybody else because he could fly, then the Thing would fall into a pit because he was so heavy etc. and then each member would face some new menace once they were "sorted".

Why sort? Other than mischievous/insane reasons, a designer may want to, say, capture certain foes for interrogation while killing others and showing mercy to still others. The above magnet trap is a good way to separate, say, fighters from everybody else. Add in a poisoned-magic-book library trap and suddenly you've got a party with no fighters and no wizards, so you can sweep in, grab the defenseless thieves and interrogate them.

Traps Not Meant As Traps By The Designing Culture

These are things which are dangerous or puzzling but were not meant to be so. To PCs, the features act like traps. These are hard to design, but interesting because if the PCs can guess the real way that (for example) the Claw Factory in the Dinosaur King's palace is supposed to work then they can learn to avoid or subvert them.

Traps Where A By-Product of the PCs Encountering Them Is That Some Work Gets Done

Basically, the traps or other features are half of a machine--the PCs interacting with them are the other half. The PCs--by interacting with the dungeon features--inadvertently make the machine work. Example: every time the PCs shed blood in a different part of the dungeon, a demon living in that part of the dungeon is enslaved to the trap designers' will.

Changer/Marker/Option Limiter

For whatever reason, the trap is not necessarily designed to kill or capture the intruder but mark or change the intruder (or the environment) for some other purpose down the line. Example: bank money that explodes in blue dye to mark bank robbers, or systems of one-way doors made so everyone trying to leave must pass a certain location where they can be robbed.

Intention-Testing Traps

Example: The very first room of a temple contains a gold idol on a pedestal. Anyone touching it dies. The idea is, if you're there to steal, then the trap activates. A real-world example is a burglar alarm that activates when a window is broken. Another example is a shrine door that only opens if you pray in front of it.

Tests of intention tend to be more interesting the lower tech/magic they are. And harder to make up.

Environmental/Accidental

The feature acts like a trap but was not put there by an intelligent hand--a stalagtite falls, the ice cracks, etc. Again, not too different from Flawed Traps.

Pseudo Traps

Looks like a trap but isn't. Typically the in-game reason is the designer doesn't have the resources to make a real trap but wants to scare people off.

Why Did The DM Put The Trap There?
So those are the reasons for a trap inside the game world, let's take a look at reasons outside the gameworld...

These are what the traps, in effect, do to the game. How the mechanism of the trap determines what happens to the game. (If you're confused, you'll see in a second, so hold tight..)

As an example, let's look at a typical trap:

Here's a tripwire. If the PCs say "I check for traps" and roll right and/or they say "I am feeling ahead on the floor with my ten foot pole" they'll find it. If they don't, it activates and axes fly outta the wall and do d8 damage.

This trap tests several things, overlapping:
-Caution (remembering to say "I check for traps" or use the pole)
-Luck (rolling well on the check-for-traps roll or on the damage roll)
-Stats (certain characters will be able to survive even if they take 8 damage, some characters will have a bonus to their "detect traps" roll)

Most traps test several things--or, rather, test one and if you fail it, test another. I'm going to try to break down all the different kinds of things a trap could be there for, in the game sense...

Again, if you think I missed any, leave a comment.

Tests of Knowledge

These test whether the players (not PCs) know some real-world or in-game fact(s). Like: an electricity trap that can be circumvented by using insulation, or a trap that tests whether players know that sulfuric acid plus nitric acid equals nitroglycerine. Note that testing whether the PCs know this stuff would be....

Tests of Stats

If a PC is described in a certain way on paper, s/he can circumvent the trap. Like: anyone with a 17 or higher strength can escape trap x or any wizard will be able to identify substance y.

Tests of Luck

Roll well, you survive, or: go left instead of right (and no clues beforehand which is better) and you survive.

(Obviously many newer school mechanics are combined luck/stats tests, with maybe a little thoroughness test thrown in.)

Tests of Lateral Thinking

There's treasure stuck to the center of a 30' tall ceiling. Shooting an arrow into the ceiling with a rope tied around it won't work. What do you do?

These kinds of traps are some of the hardest to devise but most fun to run. There must be no single obvious solution but more than one possible solution. And the hope is the PCs will think of something you didn't

Tests of Thoroughness

Searching the pile for 4 hours reveals nothing, searching for 5 hours reveals...something! Or: if the PCs have already found the idol in Room Q then Room Z a breeze, if not, they all die. If it's a pure thoroughness test then it's testing something any player would know to do, it's just about whether they do it enough.

Tests of Caution

Like tests of thoroughness, but applied specifically to situations of looking before leaping, dotting eyes and crossing T's, etc.. The bridge is rickety, the doorknob is coated in poison, etc.

Tests of Restraint

Addendum from John:
John said...

There's another category of traps that you didn't mention, although it's related to the caution trap: the curiosity trap.

This is where there's a mechanism with a clear means of activation, but no way of knowing what it does (i.e. it's untestable). It's obviously a trap, the players know it's a trap, and you just fucking dare them to activate it anyway.

Examples: the bell and hammer with a little plaque reading "please do not ring this bell", the Big Red Button, the door with all the locks on the outside, etc.

I think John's curiosity trap is kind of a subset of the caution trap--the test of caution may or may not be clued and may or may not be testable and may actually reward inspection on some level--i.e. there may be a right way to get past it. The "curiosity trap" is a caution test that is always untestable and always clued. And the thing you're "supposed" to do to it is usually temptingly obvious.

The PCs may think there's a reward behind the obvious warnings of the curiosity trap, however, so they're really resisting all kinds of urges (greed, for example), so you might rather call it a Test of Restraint.

Tests of Boldness/Decisiveness

The opposite of tests of caution. The PC needs to take action immediately upon encountering the feature or else get hurt. Mixing tests of boldness with tests of caution is the mark of a truly sadistic DM. ("But the last 3 were illusions, shouldn't we...""FUCKING JUMP!!!")

Tests of Role-Playing

These require the PC to interact/talk to the dungeon feature as if it were an NPC and do so in a convincing manner. Note that if the talked-to feature has some counter-intuitive way of reasoning with PCs and is untestable and unclued--i.e. the talking door is unfailingly polite but the trap will go off unless you are vulgar and rude to it--then this is really more of a test of luck than role-playing.

Party Game Tests

These are traps which require the player to meet some real life challenge, like: it's a maze filling with chlorine gas. You hand the PC a printout of a maze and a pencil and say if they can solve it in less than a minute they survive. Or the situation is one requiring cooperation and planning but the players are not allowed to talk to each other while solving it.

Other Creativity Tests

The feature has a time limit or other performance limit and the PC is required to come up with some creative thing off the top of their head in order to get past the trap. Like the Manticores-are-soothed-by poetry schtick. More common in NPC interactions than traps per se but anything an NPC can do a talking pit trap can do, too, so I included it here.

Tests of Preparedness

These basically test whether PCs brought standard gear: ropes, torches, grappling hook, etc. If the thing required to get past the trap is nonstandard and couldn't have been anticipated it's really more of a test of luck or something else.

Tests of Resource Management

The resource could be time, light sources, food, water, etc. Any extended stay in isolation will test this. A trap that makes it impossible for the PCs to escape a room for one week is an example here.

Tests of Perceptiveness

The key to getting past this trap would be noticing something the GM said (or didn't say). Wait...the door's locked from this side but none of the guards we just killed had a key?

Tests of Memory

The DM reveals some important info (not flagged as such) and, later, the PCs are going to wish they remembered what that was...

Logic Tests

Like lateral-thinking tests but usually simpler in set-up--the PCs are intentionally limited in the resources they can bring to bear. There's possibly only one solution. One example would be the old: two-guards-one-always-lies-one-always-tells-the-truth-two-paths-one-is-certain-death-you-can-ask-the-guards-one-question-what-do-you-ask? puzzle.

Cooperation Tests

richard said...

Another category? Party co-operation traps. Every episode of Sailor Moon or G-Force is this: work together or fail...you've added a time limit to the dungeon, now they have to guess and map and shout their way out. Or rope together to scale the slippery wall, or extraordinary trust/sacrifice traps: one PC has to drown/catch on fire to hit the magic button, and trust his mates will save/resurrect him.

Plot Device Traps

This is a kind of trap that isn't so much there to test the players or PCs but to introduce a wrinkle into the game from there forward. Tripping the trap splits the party or makes half of them stick to the wall or makes the wizard mute or what-all. While almost all traps have this potential, a pure plot device trap is one that is guaranteed to affect the party in some way.

Atmospheric/Clue Traps

These are real traps (in the fiction of the game) but are ineffective. They're usually just there to signal that "this is a place that has traps".