Running A Mystery

By Green

There are many types of sessions that can be run in any given system, and, for similar reasons, there are many types of sessions that any given table would like to play. The most common of these is probably the combat-heavy session, one where the party bounces from combat encounter to combat encounter, felling untold numbers of enemies or running from them as the GM permits. One of the more rare types of sessions, or better put, arcs, is the investigation. This is for a great number of reasons, but perhaps the biggest hurdle is in how one goes about creating and running a mystery. In this article, I will discuss something of a guide that should help any prospective GM get started on running a proper Whodunnit.

The first thing to do, and should actually be a subject to revisit throughout the writing process, is to figure out what actually happened. This series of events will be referred to as “The Truth,” and it should be exactly what occurred and what the party is trying to figure out. This is a good idea for two reasons: the first is that it helps guide your creation process for clues that the party could use, and the second is that if a player suggests or asks about something that would make sense for the series of events you had in mind, you can ad-lib better. As with anything involving GMing, “The Truth” should not be set in stone and should be allowed to change as the arc evolves. Perhaps the party missed some important piece of information, or the reverse, you made it too easy. Never be afraid to go off-script.

A mystery at its core is a situation where there is a lack of information. When people ask for information about what happened, generally it comes in the form of the 5Ws and H questions: Who, What, When, Where, Why, and How. Conversely, missing an answer to some of those questions is what creates a mystery. Being told that the bandits who raided the town last week are somewhere in the forest is not really a mystery, as you’re only trying to establish a single question: the where (as in, where are the bastards?). In comparison, a mystery involving the discovery of a dead body leaves large gaps in the who (both in who did it and who this dead body was potentially), where (did the murder actually occur here or is this merely the dumping ground), when, why (the motive), and how. Similar to the last suggestion, it can be helpful to establish what information the party is missing or has and compare it to “The Truth”. This can help prevent situations where you, the GM, think that connections have been established that actually haven’t been. It can also help to manage the scope of the mystery itself. Mysteries with more unanswered questions tend to be more complicated and should be left to parties with both a greater desire for and capability to solve mysteries.

The previous few points are all well and good, you might be thinking, but how does one go about creating the actual mechanics of a mystery? The nuts and bolts of all of this are dependent on the game system, but obviously, your more out-of-combat skill monkey-type characters should excel in these situations. The main things to keep in mind are your clues, threads that your players can pull on to arrive at the truth. Clues act as things that point your party in the right direction to fill in the missing blanks of information. Generally, the rule of 3 is a good idea, that each piece of missing information should have 3 clues that the party can acquire that establish the truth of what happened. “But my robbers/murderers wouldn’t leave clues! They’ve read all the true crime dramas and used magic to cover up all their tracks!” is a thought you might be having. To address this, it is important to remember how combat encounters are balanced. Most combat encounters are balanced so that the party can win if they plan properly or are built well. Not leaving clues behind is the equivalent of throwing a level 1 party against Tiamat; it will only serve to frustrate the party. To help with keeping track of your clues, it might be helpful to construct “clue trees,” a more visual diagram of how the clues you are leaving behind help point towards the truth. Related to this is the idea that a GM should limit the amount of information to be obtained from a singular source. It can be less fun when there is a witness who is able to answer each and every question that the party has. If such an easy piece of evidence is at hand, then what point does the party serve?

On a similar note as combat encounters, it’s important to remember that, in systems where combat can happen or is common even, some characters might be built towards combat and not towards peering through a magnifying glass at bits of hair. Similarly, some players might have shown up to your game expecting to stab something, not figure out who stabbed someone else. It’s important to keep in mind the desires of your players when building any encounter, and it is doubly so when building something as complicated as a mystery. Throw in the occasional combat encounter to give your barbarian type characters something to do. I would offer a word of warning about crime show-esc “The heroes give chase to an escaping villain,” only because the writer of a TV show doesn’t have to deal with their players getting mad at them for railroading the villains’ escape. You either need to have a contingency plan in case that villain actually gets captured, or potentially deal with the fallout that’s associated with railroading.

Now that you have read all of these bits of advice, I have one last thing to tell you. Never be afraid to give your players hints. People actually in the situation tend to notice things that players being narrated at won’t. Similarly, players playing characters who are far wiser or more intelligent should be given some sort of boon to help bridge the gap between in-game and out-of-game intelligence. We play these games to feel like amazing, smart, and competent people, not because we actually are.

---

About the Author

Green’s been playing TTRPGs of one form or another since 2017. Only recently however has he branched out into game systems other than D&D 5e in 2022. He’s experienced Fallout: The Roleplaying Game, Animon, Konosuba, Shadowrun 5e, Pathfinder 2e,  and the Transformers TTRPG. The bulk of the experience he’s had has been with D&D 5e, having the privilege to do quite a lot of GMing for 5e, including the creation of three homebrew campaigns, but not so much for the other systems. Interestingly, se has GMed more games of Fallout 2d20 than he’s been a player.