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What makes a good Cthulhu Mythos scenario?


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What makes a good Cthulhu Mythos scenario?

All good scenarios from any roleplaying game have certain aspects in common, but Cthulhu Mythos scenarios definitely have certain elements that set them apart from other games. When comparing the many "classics" and "favorites" Cthulhu scenarios from over the years, most of them are very distinct from each other. These variable elements are often points on an axis (like the level of Cthulhu mythos in an adventure can range from a werewolf to Cthulhu himself, but neither extreme of the axis precludes a good Cthulhu scenario).

In addition, scenarios have the ultimate swing factor of the ability and style of the Keeper. A great Keeper can make gold from the worst scenario, while a great scenario can be too much for a beginning Keeper to pull off in the way they hoped.

The complaint most often leveled against scenarios is that a scenario "needs work", as in the Keeper will have to add or modify many elements to make it workable... but is this for the specifics of their group, or their own Keeper style, or just because the scenario is poorly written or organized?

Aside from these options that can vary in degree, there are certain major elements that ARE required in all Cthulhu Mythos scenarios.


Major Elements:








Plausibility (to frame horror)


Strong structure


Axis Choices:

Possibility of success

Level of Cthulhu Mythos reference



Are there other Major Elements that you would list as necessary for a good Cthulhu Mythos adventure? In your favorite scenarios, what elements made them your favorite? (But try to avoid spoilers in your examples, please!) And what things that "needed work" in a scenario do you wish all scenarios included?

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I would add good visually interesting scenes to that list, though I know sometimes scenarios run the danger of becoming just a string of scenes (my own included). A good mystery and intriguingly different clues are almost a must, as far as I'm concerned. Unfortunately, over the years I found some of my own pieces lacking in certain other areas (I was never one to go overboard on handouts, for instance). I also liked to make my plots plausible, hopefully devoid of coincidence and over-the-top elements: I grounded my stuff as much as possible.


I think things like roleplaying in particular are the business of the GM and players. My philosophy was to come up with a good story, good clues, some killer scenes, and a likely conclusion (or two). I left the roleplaying and how the Keeper incorporated the scenario into his/her individual campaign to them. I think every single scenario requires some work by the Keeper, especially if he's trying to work his player characters into the story somehow. I figured my job wasn't to try and anticipate every type of PC that might be used in the scenario, that the Keeper would handle that. Same goes for scenario hooks. People are always bitching about how this or that scenario's hook is "lame". Well, they're hard to do, especially if you're trying to think of something generic enough for most GMs and PCs to use.


Another thing all good scenarios need is a solid, informative precis of the scenario, up front, within a page or so of the beginning. A good Keeper's Info section should cover enough bases for the GM to see what happened before, what's happening now, and what is likely to happen in the course of the adventure. Hopefully without omitting some important NPC, event, or creature that shows up out of nowhere in the text that is crucial to the story.


My 2 cents anyway.

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For me this is overthinking it.

A good scenario is one your players enjoy.

A scenario build is just something to deviate from when the players discover a brand new direction to shear off on. 

For my builds (from Call of Cthulhu to Fear Itself) I build the Who, What and Why. Add supporting cast and a series of encounter/events. 

Once I introduce the players into the opener, everything changes depending on PC actions.

Too much planning is a waste.

D&D style RPGs benefit from excessive detail. Horror/investigation style games suffer from excessive detail.

Just my opinion if course.

Edited by Spence
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Totally agree with Spence. The reason for this is:

1. Excessive details in D&D style adventures make the adevnture more colorful, give the villain a more understandable motivation, there is more to see and interact with for the players: And if push comes to shove (as it will) - solve the problem with spell and steel!

2. In investigative scenarios, who are by definition full of details because teh players try to solve a horror or murder mistery, you get even more details on all the details on top of everything. And in the end you have a group of players that can't see the vampire becaus eof all the bats around - no resolution, only confusion is the end.

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I also agree with Spence.  In my  experience just what makes a good adventure can vary quite a  bit depending on the actual  adventure and players.  Sometimes more freeform adventures work out better than carefully  plotted ones. Horror adventures in generally tend to be more successful in non-horror RPGs than in horror RPGs, as in a horror RPG the players come of expect the weird and supernatual take stuff more matter of factly than in a non-horror RPG . 


I'm also not a fan  of the overly descriptive D&D  style. In many cases I find such descriptions to by hammy attempts at story telling  and mood setting, but usually inappropriate under the circumstances. For instance a three paragraph description of a room, right down to the wallpaper, despite the  all the mon sters that would have attracted the PCs attention and taken thier minds off of the decor.

Chaos stalks my world, but she's a big girl and can take of herself.

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On 12/3/2019 at 4:34 PM, JaredS113 said:

What makes a good Cthulhu Mythos scenario?

For me, adding the Mythos to anything has never improved that thing.


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Simon Phipp - Caldmore Chameleon - Wallowing in my elitism since 1982. Many Systems, One Family. Just a fanboy. 


Jonstown Compendium author. Find my contributions here

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When I run a scenario, I don't want my players to immediately guess what they're dealing with. Ideally, they should be mystified, worried, and maybe confused.  I do want them to figure out what's going on somewhere in the middle of the action, and I definitely don't want the scenario to gratuituously swap one monster into the natural niche of another without foreshadowing that the players' metagame preconceptions may be wrong.  As an example, suppose that the investigators are looking into strange disturbances at an old cemetary.  The players (not necessarily the investigators) may very well expect ghouls to be involved.  If it turns out that the issues were caused by a pod of cthonians burrowing around underneath the place, I expect some clues will give the players a hint of what they're truly facing, even if the clues don't give away the whole show. 

I also like to see enough "Scooby Doo" shenanigans to keep them honest:  They might go in expcting ghouls, and instead discover that thieves are trying to tunnel into a bank vault next to the cemetary.  A scenaro like that should have some other twists:  Perhaps the thieves are trying to get into something less cliched than a bank vault, and perhaps they want a payoff that isn't as simple as the bank's contents...  If something is the first thing you think of, it's better to put something else into your scenario..

Not every cult is Cthulhoid, and not every town has a cult.  Not everyone who suspects the truth is a cultist, and not every cultist is a fanatic.

Edited by Sir Wulf
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Uncanny valley. Cthulhu wasn't scary because he was huge and had lots of tentacles, Cthulhu was scary because of the effect he had on our fellow humans - he made them something other than human. They still looked human, but they were different to us, unpredictable, alien.

If there's a monster out there, humans have been banding together against the dark since before we were human. But what if you can't trust your friends? What if the alien horror might already be amongst you, hiding behind the face of a friend, just waiting until you are isolated, alone and vulnerable? 


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