I love running mysteries. I am not talking about the big, overarching, hey look at me I am trying to be Lost type of mystery, but rather the good old gumshoe-style story. The nice thing is that a story like this can slip easily into any genre, from the tux-and-tie of a spy story, to the crown-and-sword of a fantasy campaign. It just takes a bit of costuming, and you can dress a mystery up pretty much any way you like.
Let’s take a quick look at how a mystery is different from a dungeon crawl. The main difference for me is that one is active and the other is reactive. In a dungeon crawl, the party arriving in the dungeon is the thing that is happening. Sure, they may be there as a response to some action a villain has taken. You would think this would put the party in control of the story, but instead it really puts the narrative in the hands of the GM.
Why? Because no matter how big the dungeon is at any point along the road, the only real choice the party has is which door to open next. A mystery, on the other hand, makes the players react. Something bad–or perhaps something that seems to be bad–has happened, and the party needs to figure out who did it, and often why.
This puts them in the driver’s seat. They can latch on to any little bit of information you have given them and try to use that to get some answers. One of the advantages of a mystery is that the story stops being a set of railroad tracks that guide the party to where you want them to be. Instead, the story becomes part of the reward system.
You can hand out information about what is going on when players do something right, whether it is something you planned or not. If they think of an interesting and effective way to get information that is outside of what you had planned, give them a clue. They get an ah ha moment, then they have to figure out what to do with it.
So what do you need to know to run a good murder mystery adventure?
What makes a mystery fun is the obfuscation, but that is not where we want to start. We need to start at the center of thing. Who did What to Whom and Why. Before we can place the red herrings, choose the McGuffins, and hide the murder weapon, we need to know the basics.
From here we start the process of obfuscation. This usually introduces one or more new who’s to the equation: the suspects. These are the people who have a reason to want the victim gone, or, at least appear to have a reason. These suspects don’t take much to flesh out, either: a name, a motive, a few phrases that describe them, and an alibi.
The other thing you will need for a good mystery is the clues. Here is a place where it is easy to make a mistake. If you leave too few clues, you force the players to move along a path you have built for them. A mystery adventure should feel like the players are building their own roads. On the other hand, too many clues, and the case is too easy.
I usually solve this by coming up with a few clues that the players can investigate to start things off, and working organically from there. I know what happened and I know who did it, so I know what evidence to plant as things progress. Now, not every clue you plant needs to pan out to be a red herring that gets the party looking the wrong way at the right moment, but it can be great fun.
There is a lot more to say about mysteries and how to craft them, but this is a lot to take in. For now, let’s take a moment to recap. A mystery is a great way to let the players off the tracks for a bit to do their own thing. This means there must be more than one way to solve the mystery. We can do this by keeping things organic and keeping our notes simple: Who did What to Whom, and why are the other suspects innocent?