Improvising in the Horror and Mystery Genres


Since discovering Urban Shadows at Origins a few years back, I’ve come to enjoy the low-prep, play-driven style of PbtA games, and it’s become one of the most enjoyable systems for me to run. I appreciate the prompts that the moves give the GM to take and run with, and I especially like to be surprised by the story instead of feeling disappointment when players miss the material I prepared for the adventure: the secret rooms of the dungeon, the skeletons in the closets of the NPCs, and so on.

I also enjoy investigations and scary scenarios in particular, and I’m curious how the mystery and horror genres lend themselves to improvisational play in general. I have found that games like Gumshoe and Dread still require a significant amount of prep, and I’d love to offload that onto the players via moves and playbook questionnaires, plus a hefty dose of GM improvisation to tie things together. Besides Tremulus, are there any other PbtA games or story games that facilitate horror and mystery scenarios, explicitly without preparation?

Do you think that it’s even possible to pull off a good investigation or a good scare without meticulous plotting? I’d love to hear your thoughts, recommendations, and any hard-won advice you have to share. Thanks!


I think you can increase tension and scare people.

With 6- you don’t have to use it straight away, or to even have them fail their task. You can just smile and stash it for later. This makes it easy to stash a few for the following -

  • In horror they often do things like - nervous person outside in spooky area, rustling in bushes, hero looks - BAM! raccoon jumps out. Hero yelps/gasps, another hero rocks up, then laugh, head back to the car/house and THEN they find the body/monster.

  • Another thing they do is weather gets colder and overcast, the lights in the street slowly go out. Things get quiet in the forest. - After these things start, you don’t have to reverse them, you can keep rolling with whatever events and just remind them later the lights are still out or the clouds rumble over head, so the players know the danger/mystery is not over.

You don’t even need a 6- for setting the scene, or if you want to say sorry your out of mobile reception’’ or ‘‘when you go to cast a spell you get a chill down your spine’’. - its just flavor, but it works for you.

Being able to do this without preparation would require some genre saturation (watch a bunch of films or listen to audiobooks)


You might want to check out @SinisterBeard’s Apocalypse By Moonlight supplement in Codex: Moonlight.


A good scare is easy. A good investigation is not.

I’ve found most prep is in the form of fronts and sorta improvising/moving the front from the ephemeral to the real. It’s easy to draw from that to make things scary – just introduce the worst thing at the perfect time.


This is a topic that is very close to my heart (it was the topic of the very first episode of The Gauntlet Podcast!) I’ll start by saying the PbtA by Moonlight thing that @shanel recommended is very good and def worth looking into. I can send you the PDF of Codex - Moonlight if you don’t have it (just DM me).

As a general matter, I very much enjoy enjoy what I call “emergent” mystery games, which is to say games where the mystery unfurls sort of organically at the table. In that sense, the “thrill” of the mystery is not necessarily what the characters are experiencing in-fiction, but rather what the players are coming up with on their own. A great example of a game that does this is Psi*Run by Meg Baker.

For a more traditional, GM-driven approach, I think the best thing you can do is simply come up with a list of clues that can be air-dropped wherever you need them. So, Graham Walmsley used to produce a supplement for Cthulhu Dark called Darkest Depths, and the idea behind it is you could create a Lovecraftian mystery that adhered to the classic structure of such mysteries, but the actual clues the characters find can be found anywhere they decide to look. Essentially you can’t find Clue Type C until you have found X number of clues in Type A or B. This is a kind of middle approach that I prefer: you have to do some prep, but it’s a loose enough prep for you to still be improvisational and to give the players a lot of freedom in their approach to the investigation.

Here is an example of such a mystery structure I did:


So I built a whole game for this, heavily piggybacking on a structural base of an obscure solitaire variant to model a slurry of interconnected clues. It’s very noir in mode, so if matchsmoke and Chandleresque interruptions aren’t your jam then maybe don’t look this way, but EXUVIAE will procedurally generate an entire conspiracy investigation as you play.

It’s the forties. You live in a bayside town that’s secretly under the control of an insect cult and tonight you’re going to prove it.

My biggest takeaway for other games is to mercilessly reintegrate earlier material, especially if it was created by the players, and especially if it makes no sense to.


Please take a look at We Used to be Friends. It’s a Veronica Mars simulator that has a nested mystery structure where you create a long-term mystery for your PC during creation but play one-off ‘local’ mysteries in each session. It’s more straight-up procedural than horror, but I see how you could easily tweak it to add spooky mysteries.

We Used to be Friends


That’s what I’ve been doing in my few forrays into mystery/horror dm-ing.

Another technique I learned from Jason is repetition of a theme or event. It doesn’t by itself seem to create horror, but it definitely hits mystery, and if you tie it into something else it can be tied into a powerful horror pay off.

I… May have overdid the payoff in my first application of this idea in a f2f dungeon world campaign; very nearly had a TPK I wasn’t intending (all players were down to 1 or 2 HP, one of them hit black gates but made it through).


You may want to check out also the GMless game Lovecraftesque


I finally had a chance to run Lovecraftesque this week and it was exactly what I was looking for. Thank you very much for the recommendation! My fellow players and I had a blast.


@rabalias and @BeckyA - looks like you’ve got another satisfied customer. :wink:


To save you the search: Dark Depths by Graham Walmsley


Best news ever :slight_smile: