Mysteries: It's ok if the Players Get Stuck
I’ve played a couple of mystery-solving games recently, and read a bunch more. A trend I keep seeing in discussions about them is the argument that mysteries are really hard to run.
I don’t quite agree. I do find dedicated mystery games take a little more prep, but not drastically more. I think most of the problems people have when running mysteries come from one core problem: The GM does not consider failing to solve the mystery a valid outcome, and failing to solve the mystery does not advance the game state.
People are worried about players missing clues or getting on the wrong track. If you are worried about the players getting stuck, you either have to prep a bajillion paths to the right answer or have mechanics to nudge the party in the right direction. You don't have to do either of these if failing is a valid outcome. There are two approaches I like here, depending on the game.
Sometimes the Mystery Doesn’t get Solved

This approach works for everything but dedicated mystery games. Games where there may be mysteries, but solving mysteries is not the point of the game. In a sandbox fantasy game, maybe the player's goal is to defeat the sorcerer king. I might include a bunch of clues about the cult he got his powers from. If the players solve the mystery of where his powers come from, great, but if they don’t, nothing is derailed, because it's not the main thing they are doing. They can still just go fight the Sorcerer King.
I think mysteries are very easy to set up this way, as long as you are ok with the players not solving all of them. You don’t have to do the [three clue rule](The Alexandrian » Three Clue Rule), or move clues around when people miss them. Sometimes the mystery just doesn’t get solved, just like any other challenge. Sometimes the dungeon doesn’t get cleared. Sometimes the secret room doesn’t get found.
I don’t think you need to do anything special to run mysteries if they aren’t the point of the game. Just put in clues where it makes sense and be ok with it if the players don’t figure it out.
The next approach is relevant for these types of games too, but I wanted to call out that sometimes it's ok for a mystery to just go unsolved.
Make the fail state consequential
This is for games or sessions where the solving of the mystery is the point. If we meet up to play a murder mystery, it becomes more of a problem if the players get stuck. If the players get stuck in a mystery game, they can’t just go do something else. Or at least, they won’t want to.
There’s a lot of great techniques you can use to help here, like the Three clue rule, or GUMSHOE’s system of not locking core clues behind rolls. I recently read Blade Runner’s intro adventure, and it does something so obvious that I don’t know how I didn’t think of it sooner: Shit happens if the players don’t solve the mystery after a certain amount of time.

The climax of that adventure is an attack on a lab. That attack occurs at a specific time, whether the players solve the mystery or not. Solving the mystery determines how prepared they are and whether they get there before it happens. So it's ok if players chase down an incorrect lead or have trouble putting all the pieces together. The adventure comes together to a climax no matter what, and that climax will recontextualize the clues they have in a way that makes sense if they don’t have all the details right.
The adventure does include lots of redundant clues, and even an ‘I’m stuck’ button in the form of a chief you can call for tips. But fundamentally, the adventure works even if the players get stuck or reach the wrong conclusion.
This is something I would now include in any dedicated mystery game. What happens if the players fail? It should be something that either creates more evidence or resolves the mystery in an exciting but dangerous (or undesirable) way.
Examples:
- If you don’t catch a serial killer, he kills again, generating more evidence, but maybe the victim was an NPC you like this time.
- If you don’t resolve a hostage situation by finding the jewel the criminal wants, the police decide they need to raid the building. Now it's a gunfight, and the hostage might die.
- If you can’t figure out where the bomb is, it explodes. You get a taunting message on your cell phone that kicks off the next mystery. Think the Riddler from Batman.
- If you can’t figure out where the ritual is being done, the demon gets summoned. Now you need to figure out the demon's weakness.
What the consequences should be depends on the game. In some games, a shootout might be appropriate, in others an escalation and additional clues might be better.
If the players get stuck, something bad happens, and it gets the players unstuck.
Note: This works best if you track time. In Blade Runner, checking out a location takes a “shift”. The climax happens after a set number of shifts. Players don’t need to know what will happen or exactly when, but they should know that if they don’t solve the mystery, something is gonna happen eventually.
The big idea here is that a lot of the challenges of running mysteries are alleviated if failure is an acceptable outcome that either advances, or at least doesn’t halt, the game state.