How I Create My Adventures (Scenarios) for Call and Trail of Cthulhu RPG's

There is no one single way to write stories using the Cthulhu Mythos. Many authors, over the years, have created different settings based on Lovecraft's work. Some make pulp stories, mixing science fiction and magic, time travel, and wars between alien races (recently, we had Fate of Cthulhu, with time travelers heavily armed to destroy invincible strange gods and avoid the apocalypse — just like The Terminator).

Others are purists and cling to Lovecraft's classic style of writing their short stories and novels — raw and violent to the investigators' bodies and minds. So, the first step is to think about what pleases you within the range of stories from the Cthulhu Mythos. This is the starting point. If you are not familiar with the role-playing game or the works of Lovecraft and inspired authors, you can read a little bit about them or play some pre-made adventures to feel the mood that pleases you and your group. If you don't have the time for this and need to write your adventure right now, to Keeper at the next meeting with friends, I will show you how I organize the mysteries in my sessions.

Strange Events:
Creatures, Spells, and Cults

My first step is to choose the strange event in which the mystery will revolve around. The Keeper Guide and the Trail of Cthulhu books have a list of creatures and spells, as well as cult ideas.

I choose only one creature. With that, I am saying, "this one creature, alone, is capable of wiping out all of you and threatening the life on Earth — what will happen if others like them arise." Lovecraft commonly used only one creature (except for some novels where it includes an entire race), or perhaps there are servants of that creature. However, the mystery will revolve around a single monster and the consequences of its existence and actions.

When I prepare a story on a no Lovecraft style, or with pulp elements, where the Investigators can easily face the creatures using weapons, magic, scientific and alien devices, I create mysteries that happen with various creatures or some strange events.

I read about the monster in the RPG book and look for references in other publications or on websites. I usually read the tales in which the creature appears or buy audiobooks from the novels to listen to during the week.

Another thing I do is, instead of including a creature, I just put a cult or someone performing powerful magic. Perhaps there is not a being that meets the will of the cult, and they are just a group of madmen who practice atrocities — who knows they may even end up attracting the attention of some monster with their unbridled actions. Also, if that happens, the adventure initially revolves around insane humans, and the mystery reveals itself deep, showing that they were able to awaken something evil (an arc for a campaign).

Also, poorly executed spells can bring many misfortunes, as this mystical force is unpredictable. They can call a creature which does not meet the sorcerer's will, killing him and those who follow him, leaving the beast free to fulfill their own desires on Earth. Other times, poorly executed spells can create catastrophic situations, such as climate change, mental control of people, or the death of innocents. The spell lists in the basic Call of Cthulhu Keeper Guide and Trail of Cthulhu book can be an excellent source for inspiration.

Eventually I create new monsters, spells and cults inspired by those that already exist. Sometimes I mix with traditional legends and create an abyssal blood-eating, able to send people nightmares, for example.

Mystery Takes Shape

Now that I have chosen the strange event (be it a creature, cult, or supernatural situation), I write essential events in a list, starting from the moment when the existence or action of the monster or cult happened, or a strange situation occurs. I try to think about things chronologically. What can the appearance of that being or situation entail? I reread and modify things on the list according to new ideas, or rewrite what happened. For example:

• A crazed sorcerer casts a spell in a forest a few miles from a village, to summon a Dark Young, whom he believes to be a deity (he studied poorly written volumes and didn't quite understand what he read).
• The Dark Young appears, but kills the sorcerer and a small group of cultists who followed him.
• The Dark Young is free, living in the forest near the village, feeding on cattle, sheep, and hunters who go deep into the woods.
• A small group of people (farmers among them) from the village started to fear, worship, and offer sacrifices to the creature. They don't know what that monster is, but they believe that, by pleasing it, they will be spared.
• After 4 to 6 months, people start telling strange stories.
• Investigators hear strange stories about animals killed strangely and missing persons — a family member, relative, or friend may live in the village or have disappeared. Or they may know someone from the local who sends them a letter asking for help.

With this list of events in hand, I create a new one. This time, in the possible order of events that the Investigators will experience during the game.

• Investigators hear strange stories about animals killed strangely, and missing persons — a family member, relative, or friend may live in the village or have disappeared. Or they may know someone from the town who sends them a letter asking for help.
• They can research before they travel and discover that there are strange stories in local newspapers or hear from people that these things have been going on for almost 6 months. If they do not research before traveling to the village, they can discover things by talking with the villagers who do not worship the Dark Young. However, this draws the attention of the cultists who will attack them on one of the nights.
• They discover that a group of people, including farmers, visits the forest at night (perhaps they see a procession of them, one night, heading towards the forest, taking some animal for sacrifice or witness a meeting of them at the home of cultists, talking the details of the next ceremony).
• Cultists persecute the investigators (if they are not discreet in their actions).
• The group discovers that there is something in the forest that feeds on cattle, sheep, and hunters that go deep into the woods.
• If they enter the forest, they may discover the carcasses of animals, and humans mutilated unnaturally. They can find the remains of the sorcerer and his followers.
• The group discovers that wizards and sorcerers frequented the place and performed rituals. One of the rituals may have brought some kind of creature from another world.
• They need to find a way to stop the cult and get rid of the Dark Young. They can discover the profane books of the sorcerer who died in the forest (perhaps the books are still in the woods, buried, or at the home of some of the farmers, and they need to steal).

Using this list, I improvise the entire game session, according to what the players decide during the game.

If you are not comfortable with improvising, you can turn each list entry into a scene. Then, you write the details about each one — places, people, objects, and events. If you want to know how I prepare scenes, you can see the post where I talk about How I Prepare a Pre-Made Call or Trail of Cthulhu RPG Adventure (Scenario). Use the same method, or create your own, of preparing the scene (on a sheet, I write the title of the scene, a paragraph that I will read to the players and a dotted list with all the clues, plus notes about people, locations and notable things). Put everything in a way that you feel safe and comfortable with what you are creating. That's the most important.

And you, how do you create your mystery adventures?