Whenever you’re designing a mystery scenario, you should invariably follow the Three Clue Rule:

For any conclusion you want the PCs to make, include at least three clues.

Why three? Because the PCs will probably miss the first; ignore the second; and misinterpret the third before making some incredible leap of logic that gets them where you wanted them to go all along.

I’m kidding, of course. But if you think of each clue as a plan (the PCs will find A, conclude B, and go to C), then when you have three clues you’ve not only got a plan — you’ve also got two backup plans. And when you realize that your plans never survive contact with the players, the need for those backup plans becomes clear.

In a best case scenario, of course, the players will find all three clues. There’s nothing wrong with that. They can use those clues to confirm their suspicions and reinforce their conclusions (just like Sherlock Holmes).

In a worst case scenario, they should be able to use at least one of these clues to reach the right conclusion and keep the adventure moving.

And here’s an important tip: There are no exceptions to the Three Clue Rule.

“But Justin!” I hear you say. “This clue is really obvious. There is no way the players won’t figure it out.”

In my experience, you’re probably wrong. For one thing, you’re the one designing the scenario. You already know what the solution to the mystery is. This makes it very difficult for you to objectively judge whether something is obvious or not.

And even if you’re right, so what? Having extra clues isn’t going to cause any problems. Why not be safe rather than sorry?

EXTENDING THE THREE CLUE RULE

If you think about it in a broader sense, the Three Clue Rule is actually a good idea to keep in mind when you’re designing any scenario.

Richard Garriott, the designer of the Ultima computer games and Tabula Rasa, once said that his job as a game designer was to make sure that at least one solution to a problem was possible without preventing the player from finding other solutions on their own. For example, if you find a locked door in an Ultima game then there will be a key for that door somewhere. But you could also hack your way through it; or pick the lock; or pull a cannon up to it and blow it away.

Warren Spector, who started working with Garriott on Ultima VI, would later go on to design Deus Ex. He follows the same design philosophy and speaks glowingly of the thrill he would get watching someone play his game and thinking, “Wait… is that going to work?”

When designing an adventure, I actually try to take this design philosophy one step further: For any given problem, I make sure there’s at least one solution and remain completely open to any solutions the players might come up with on their own.

But, for any chokepoint problem, I make sure there’s at least three solutions.

By a chokepoint, I mean any problem that must be solved in order for the adventure to continue.

For example, let’s say that there’s a secret door behind which is hidden some random but ultimately unimportant treasure. Finding the secret door is a problem, but it’s not a chokepoint, so I only need to come up with one solution. In D&D this solution is easy because it’s built right into the rules: The secret door can be found with a successful Search check.

But let’s say that, instead of some random treasure, there is something of absolutely vital importance behind that door. For the adventure to work, the PCs must find that secret door.

The secret door is now a chokepoint problem and so I’ll try to make sure that there are at least three solutions. The first solution remains the same: A successful Search check. To this we could add a note in a different location where a cultist is instructed to “hide the artifact behind the statue of Ra” (where the secret door is); a badly damaged journal written by the designer of the complex which refers to the door; a second secret door leading to the same location (this counts as a separate solution because it immediately introduces the possibility of a second Search check); a probable scenario in which the main villain will attempt to flee through the secret door; the ability to interrogate captured cultists; and so forth.

Once you identify a chokepoint like this, it actually becomes quite trivial to start adding solutions like this.

I’ve seen some GMs argue that this makes things “too easy”. But the reality is that alternative solutions like this tend to make the scenario more interesting, not less interesting. Look at our secret door, for example: Before we started adding alternative solutions, it was just a dice roll. Now it’s designed by a specific person; used by cultists; and potentially exploited as a get-away.

As you begin layering these Three Clue Rule techniques, you’ll find that your scenarios become even more robust. For example, let’s take a murder mystery in which the killer is a werewolf who seeks out his ex-lovers. We come up with three possible ways to identify the killer:

(1) Patrol the streets of the small town on the night of the full moon.

(2) Identify the victims as all being former lovers of the same man.

(3) Go to the local butcher shop where the killer works and find his confessions of nightmare and sin written in blood on the walls of the back room.

For each of these conclusions (he’s a werewolf; he’s a former lover; we should check out the butcher shop) we’ll need three clues.

HE’S A WEREWOLF: Tracks that turn from wolf paw prints to human footprints. Over-sized claw marks on the victims. One of the victims owned a handgun loaded with silver bullets.

HE’S A FORMER LOVER: Love letters written by the same guy. A diary written by one victim describing how he cheated on her with another victim. Pictures of the same guy either on the victims or kept in their houses somewhere.

CHECK OUT THE BUTCHER SHOP: A broken crate reading DANNER’S MEATS at one of the crime scenes. A note saying “meet me at the butcher shop” crumpled up and thrown in a wastepaper basket. A jotted entry saying “meet P at butcher shop” in the day planner of one of the victims.

And just like that you’ve created a scenario with nine different paths to success. And if you keep your mind open to the idea of “more clues are always better” as you’re designing the adventure, you’ll find even more opportunities. For example, how trivial would it be to drop a reference to the butcher shop into one of those love letters? Or to fill that diary with half-mad charcoal sketches of wolves?

The fun part of all this is, once you’ve given yourself permission to include lots of clues, you’ve given yourself the opportunity to include some really esoteric and subtle clues. If the players figure them out, then they’ll feel pretty awesome for having done so. If they don’t notice them or don’t understand them, that’s OK, too: You’ve got plenty of other clues for them to pursue (and once they do solve the mystery, they’ll really enjoy looking back at those esoteric clues and understanding what they meant).

Continued tomorrow…

For the GUMSHOE system (used in The Esoterrorists and The Trail of Cthulhu), Robin D. Laws decided to get rid of the concept of needing to find clues. In each “scene” of an investigation scenario, there is a “clue”. It’s automatically assumed that the investigators will find this clue.

This removes three of our four chokepoints, leaving only the necessity of using the clue to make the correct deduction (i.e., the deduction which moves you onto the next “scene” where the next clue can be imparted). And, in the case of the GUMSHOE system, even this step can be tackled mechanically (with the players committing points from their character’s skills to receive increasingly accurate “deductions” from the GM).

This is a mechanical solution to the problem. But while it may result in a game session which superficially follows the structure of a mystery story, I think it fails because it doesn’t particularly feel as if you’re playing a mystery.

Laws’ fundamental mistake, I think, is in assuming that a mystery story is fundamentally about following a “bread crumb trail” of clues. Here’s a quote from a design essay on the subject:

I’d argue, first of all, that these fears are misplaced, and arise from a fundamental misperception. The trail of clues, or bread crumb plot, is not the story, and does not constitute a pre-scripted experience. What the PCs choose to do, and how they interact with each other as they solve the mystery, is the story. As mentioned in The Esoterrorist rules, we saw this at work during playtest, as all of the groups had very different experiences of the sample scenario, as each GM and player combo riffed in their own unique ways off the situations it suggested.

But, in point of fact, this type of simplistic “A leads to B leads to C leads to D” plotting is not typical of the mystery genre. For a relatively simplistic counter-example, let’s return to Sherlock Holmes in A Study in Scarlet:

WATSON: “That seems simple enough,” said I; but how about the other man’s height?”

HOLMES: “Why, the height of a man, in nine cases out of ten, can be told from the length of his stride. It is a simple calculation enough, though there is no use my boring you with figures. I had this fellow’s stride both on the clay outside and on the dust within. Then I had a way of checking my calculation. When a man writes on a wall, his instinct leads him to write above the level of his own eyes. Now that writing was just over six feet from the ground. It was child’s play.”

This is just one small deduction in a much larger mystery, but you’ll note that Holmes has in fact gathered several clues, studied them, and then distilled a conclusion out of them. And this is, in fact, the typical structure of the mystery genre: The detective slowly gathers a body of evidence until, finally, a conclusion emerges. In the words of Holmes himself, “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.”

What is true, however, is that in many cases it is necessary for many smaller deductions to be made in order for all of the evidence required to solve the mystery to be gathered. However, as the example from A Study in Scarlet demonstrates, even these smaller deductions can be based on a body of evidence and not just one clue in isolation.

This observation leads us, inexorably, to the solution we’ve been looking for.

Continued tomorrow…

Mystery scenarios for roleplaying games have earned a reputation for turning into unmitigated disasters: The PCs will end up veering wildly off-course or failing to find a particular clue and the entire scenario will grind to a screeching halt or go careening off the nearest cliff. The players will become unsure of what they should be doing. The GM will feel as if they’ve done something wrong. And the whole evening will probably end in either boredom or frustration or both.

Here’s a typical example: When the PCs approached a murder scene they don’t search outside the house, so they never find the wolf tracks which transform into the tracks of a human. They fail the Search check to find the hidden love letters, so they never realize that both women were being courted by the same man. They find the broken crate reading DANNER’S MEATS, but rather than going back to check on the local butcher they spoke to earlier they decide to go stake out the nearest meat processing plant instead.

As a result of problems like these, many people reach an erroneous conclusion: Mystery scenarios in RPGs are a bad idea. In a typical murder mystery, for example, the protagonist is a brilliant detective. The players are probably not brilliant detectives. Therefore, mysteries are impossible.

Or, as someone else once put it to me: “The players are not Sherlock Holmes.”

Although the conclusion is incorrect, there’s an element of truth in this. For example, in A Study in Scarlet, Sherlock Holmes is investigating the scene of a murder. He discovers a small pile of ashes in the corner of the room. He studies them carefully and is able to conclude that the ashes have come from a Trichinopoly cigar.

Now, let’s analyze how this relatively minor example of Holmesian deduction would play out at the game table:

(1) The players would need to successfully search the room.

(2) They would need to care enough about the ashes to examine them.

(3) They would need to succeed at a skill check to identify them.

(4) They would need to use that knowledge to reach the correct conclusion.

That’s four potential points of failure: The PCs could fail to search the room (either because the players don’t think to do it or because their skill checks were poor). The PCs could fail to examine the ashes (because they don’t think them important). The PCs could fail the skill check to identify them. The PCs could fail to make the correct deduction.

If correctly understanding this clue is, in fact, essential to the adventure proceeding — if, for example, the PCs need to go to the nearest specialty cigar shop and start asking questions — then the clue serves as chokepoint: Either the PCs understand the clue or the PCs slam into a wall.

Chokepoints in adventure design are always a big problem and need to be avoided, but we can see that when it comes to a mystery scenario the problem is much worse: Each clue is not just one chokepoint, it’s actually multiple chokepoints.

So the solution here is simple: Remove the chokepoints.

Continued tomorrow…

What the hell happened to April?!

Meanwhile, in other news:

I will be starring as Inspector Colquhoun in Agatha Christie’s The Hollow from May 9th to June 1st at the Mounds Theater in St. Paul.

Fridays – Saturdays at 7:30pm
Sunday Matinees at 2:00pm
Pay What You Can Night – Monday, May 19th, 2008 at 7:30pm
Audio Described Performance – Sunday, May 18th at 2:00pm

An unhappy game of romantic follow-the-leader explodes into murder one weekend at the Hollow, home of Sir Henry and Lucy Angkatell. Nearly everyone has a motive and most had the opportunity. Enter Inspect Colquhoun and Sergeant Penny to solve the crime!

It’s shaping up into a very fun little piece of theater. If you come to see it, please feel free to hang around for a few minutes after the show and say hello.

(No stalkers or axe murderers, please. Thank you.)

This is possible the most awesome thing in creation:

There’s also a DVD available. It’s apparently a couple years old, but I have only just discovered it.