THE SOLO

I N V E S T I G A T O R ’S
S
HANDBOOK

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fil
by PAUL BIMLER

CCREDITS:
REDITS:

Art by Dominique
Internal
Giacomo
Luigi Castellani,
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All artwork
Cover

Rueben
text by by
Signoret,
artwork by Ville
Paul
Borja
Assinen,
Patri,Dodd,
Klaus
Bimler
Joshua
Nikola
Toxic,
David
Tabti.
Pindado, Sofyan
Avramovic,
Danilo
Lewis
MaraSyarief,
Neira
Johnson,
Braun,
Leothefox,
William McAusland, Marco Monte, Julien Noirel, Nottsuo,
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The Star Elder Sign is © Chaosium Inc. all rights reserved.
Borja Pindado, Senecal, Dominique Signoret, and Sofyan Syarief.
It is used here with kind permission.
The Star Elder Sign is copyright © 2021 Chaosium Inc., all rights reserved.
It is used here with kind permission.
Playtested by: Vicknesh Suppramaniam, Jay Traub, Mark Olson
Playtested by Vicknesh Suppramaniam, Jay Traub & Mark Olson.
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Print on demand edition prepared by Nick Brooke, Chaosium Inc.

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 TABLE OF CONTENTS

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Chapter 1: Introduction p.1
Chapter 2: Generate a Scenario p.10

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Chapter 3: Journalling p.19
Chapter 4: NPCs p.28
Chapter 5: Mythos Creatures p.35
Chapter 6: The Verbs Table p.40
Chapter 7: Clues Table p.45
Chapter 8:
Chapter 9:
eSpooky Tables
Rumours Table
p.48
p.51
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Chapter 10: Random Event Table p.55
Chapter 11: Location Tables p.60
Chapter 12: Example Sessions p.70
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HP Lovecraft, by Dominique Signoret
(Wikimedia Commons)

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 CHAPTER 1: INTRODUCTION
Welcome investigators. The document you read is a method
It’s a rainy Saturday night and you for generating on-the-fly solo
are in the mood for some Mythos adventures for Call of Cthulhu.
action. You have had a whisky or Through a combination of questions
two and feel the ol’ itch returning. which you will pose (and answer
That hankering for uncovering using dice rolls), as well as random

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eldritch mysteries. The irresistible tables and other mechanics, you will
lure of possible insanity. You generate a scenario for yourself,
hearken to the call… consisting of events, clues,

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encounters etc.
We all want to game. All the time. The scenario will be created by you
Not just when our group gets as you play. This will enable
together, but any time that we want gradual discovery of the mystery.
to. Surely there must be a way to You may ask the question, “If I
facilitate solo gaming at the drop of don’t know the background, how
a hat, even without a Keeper. can I investigate the mystery?” The
Of course there is. answer is, that you allow the clues

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Welcome to The Solo Investigator’s
Handbook. This product was created
with the intention of providing a
and events to determine the story as
you go. The combination of clues,
discoveries and events will
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method for playing Call of Cthulhu eventually point to something, no
solo. By solo games, we mean matter how bizarre.

(Miskatonic Repository Art Pack: Curious Things)

Keeper-less games. This system can You will link all
serve as a way for you to generate these clues and
little scenarios for yourself, in events together to

Hurricane Lamp, by Mara Braun

between regular games with your weave an answer to
m

Keeper. Or, if you can’t find a the mystery you

group, this might scratch your have created. That
Cthulhu-itch until you can locate is, of course, if
one. your investigator
In 2018 I released a product for 5e doesn’t go insane
Sa

SRD named The Solo Adventurer’s first!

Toolbox. This is a 167-page The contents
supplement that generates freeform menu on the left-
solo adventures for that system. It hand side of this
went on to become a platinum pdf (access it
bestseller on Dungeon Master’s now by clicking the
Guild in the space of three months bookmarks tab: ) is how you will
and is still sitting in their bestseller’s navigate between the many tables
list at the time of writing. and resources in this book.

1
 CHEAT SHEET: SOLO INVESTIGATION METHOD
USE THIS AS YOUR REFERENCE POINT FOR SOLO
INVESTIGATION.

SETUP
1: Create one or more investigators to play with.
2: Read up on the Question/Answer mechanic (this chapter).
3: Create a scenario for your investigators. See Chapter 2.
4: Begin your journalling. See Chapter 3: Journalling, especially the Story

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Direction Table.
5: Investigation Rounds commence. Mythos Points start at 0. Continue until
either dead or insane!

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INVESTIGATION ROUND
STEP 1: Create a new time-stamped entry in your journal, and then roll on the
Story Direction table.
STEP 2: Once you have your direction (one of five directions: Downtime /
Development / Discovery / Danger / Dice Roll) then go to the subtable for that
direction, (found in Chapter 3). Whenever your character rolls or elects to have
Downtime, (such as for sleeping) roll on the Downtime Disturbance Table to see

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whether their Downtime is disturbed.
STEP 3: Every time something unsettling/scary/terrifying/petrifying happens,
add Mythos Points to the current score as directed by the Mythos Points Table.
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This will also require a Sanity Roll, as directed by the table. The Mythos Points
score can be reduced with undisturbed Downtime.
STEP 4: Using Q/A rolls, continue to interact with all the elements of your
story until you reach a dead-end or wish to know what happens next. Then,
estimate how much time has passed since the last journal entry, and use this as
the time of your next journal entry.
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STEP 5: Return to Step 1.

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Shoggoth, by Nottsuo
(CC BY 3.0)

2
 GAMEPLAY EXAMPLE investigators have different
For an example of gameplay using strengths which can possibly
the system in this book, you could complement each other. The
skip forward right now to Chapter 12 drawback is that you will have to
which contains examples of generate another character sheet to
gameplay using this system. This play with, but this is fun anyway!
will give you a look at how all the Alternately, you can check out
elements in the book can be used. drivethrurpg.com for a premade
character pack. There are a few

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CORE BOOKS
good ones.
It is a good idea to become familiar
If you choose to go it alone, you can
with the core books such as the
explore the concept of contacts for
Investigator’s Handbook and the

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your character. Information on
Keeper’s Rulebook. The rules and
contacts can be found on page 97 of
guidance contained therein will form
the Keeper’s Rulebook.
the basis of your knowledge on how
to run your solo investigation

Book, Skull, Candle, by William McAusland

(Outland Arts Fantasy Clip Inks - Spot Art)
VARIANT: B O O S T I N G
campaign. THE SOLO
INVESTIGATO
INVESTIGAT OR
N E W T O CALL OF As an alternative to running
CTHULHU?
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If you are only just getting
started with the game, it is
recommended that
multiple investigators, you could
always boost a single
investigator so that they are
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better equipped to
you read the cope with whatever
Quick-Start the Mythos throws
Rules, a at them.
handy pdf The key here is
provided free by Occupations. Give your
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Chaosium, the creators investigator two of them. Perhaps

of Call of Cthulhu. It contains all they are a journalist, but also
you need to know to get started moonlight as a private investigator.
playing CoC straight away, and is Or, perhaps they are a librarian but
available at the following link: spend their spare time on
https://www.chaosium.com/cthulhu-
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archaeological digs. There are

quickstart/ innumerable ways you could justify
them having two occupations. Many
SOLOING - ALONE OR
WITH MULTIPLE of us already do, in our day-to-day
INVESTIGATORS lives, myself included (writer -
You have a choice. You could create musician - teacher).
a single character, or you could This will enable them to gain double
create two or more investigators to the personal interest points that they
solo with. The advantage with the would normally have, and will make
latter approach is that different

3
 them a bit more able to cope with a Points, which accumulate over time,
wide range of situations. will also increase the action.
Taking this option will potentially
result in some longer-lasting INTERACTION
scenarios. If you’re fine with your In order to have a meaningful solo
investigator going insane or dying experience with Call of Cthulhu, the
within the space of a few days, then key is interaction. You need to have
stick with standard, single- as many things available to interact
occupation investigators. with as possible, which will add to

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the immersion and improve the
THE CORE OF THIS quality of the experience. This can
SYSTEM: JOURNALLING include, but is not limited to:
Journalling is what this system of

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solo investigation is centred on. ♦ Music (check out Cryo Chamber
In my dungeon-delving solo and Altrusian Grace for dark
adventure method (The Solo ambient stuff, or you might
Adventurer’s Toolbox), the discovery prefer 1920s Jazz).
of the various passages of the ♦ Handouts (if possible. See below)
dungeon, or of wilderness terrain, ♦ A blank book and writing
and travel through those areas, are implement to facilitate your

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what sparks encounters, combat, and
every other aspect of solo
adventuring. The fact that the
journalling. The more old-world
the better
♦ Props. Why not turn off the
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particular system (5e SRD) focuses lights and have a candle burning?
so much on maps provides a coherent Sets the mood surprisingly well!
framework around which to base a ♦ Old photographs. These could
solo campaign. form part of the basis of your
In Call of Cthulhu, however, maps story. Check out
don’t figure that prominently. cthulhustreasurebox.blogspot.com
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Hence, as I was working on this Lots of lovely photos and other

system, I tried to come up with a stuff.
different framework for solo ♦ Maps. These can form the basis of
investigation. The one I finally a campaign. Base your story
arrived at was time. The passage of around them.
Sa

time, as marked in a journal, is what Propnomicon.blogspot.com has a

lies at the core of this solo Call of beautiful one of Arkham,
Cthulhu system. Massachusetts, as well as many
Throughout your investigator’s day, other resources.
you will write time-marked journal ♦ Miniatures. www.rafm.com has a
entries. Later on, you will see how good range. Otherwise ,you could
rolling on the S t o r y D i r e c t i o n just google “Call of Cthulhu
T a b l e will enable you to generate miniatures”.
events for your investigator. Mythos ♦ This system and its mechanics.

4
 QUESTION/ANSWER STEP 2: DETERMINE
MECHANIC DIFFICULTY MODIFIER
If you are unfamiliar with Given all circumstances, how likely
question/answer systems, the basic is the occurrence?
idea is that the player asks yes/no
questions to find out where the story LIKELIHOOD MOD
goes next. The answers are then
determined using dice rolls. A well- Impossible -60
known one is the Mythic GM

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Emulator. You can use Mythic in
Highly Unlikely -40
conjunction with the tables in this
book, or you can use the mechanic I
Unlikely -20

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have created herein to answer yes/no
questions. This will go a long way
Possible 0
towards determining what happens
in your scenario.
Likely +20
There are a few excellent
question/answer systems out there.
Highly Likely +40

(Outland Arts Fantasy Clip Inks - Spot Art)

The Mythic system is outstanding
and has been extensively used by the

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author, and many others,
A Certainty +60

2D10, by William McAusland

in generating hours
of enjoyable solo
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With the
play. What
example question
follows is a
stripped- given above, (“Is
this town
down version
of that system. currently
peaceful?”) some
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S T E P 1 : F RAME A factors that would

YES/NO QUESTION influence the likelihood are the
The first stage is to come up with a political situation in the area, recent
question. This question needs to be events, the demographic, etc.
framed in such a way that it can be NOTE: From now on, we will refer
Sa

answered with one of the following to the question/answer mechanic and

three words: yes, no, maybe. its associated d100 roll as the “Q/A
Example: Is this town roll”.
currently peaceful?

5
 STEP 3: MAKE A D100 circumstances of the scenario, which
Q/A ROLL (adding or are trying to make themselves
subtracting the modifier)
known through your dice rolls.
Perhaps other Q/A rolls need to be
Q/A Roll Result Table
asked in order to determine what the
D100 RESULT condition is. Another way of getting
answers to a “Maybe” is to make a
1-34 NO roll or two on the Verbs table
(Chapter 6). That might add the

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35-59 MAYBE necessary detail. Or you can just
decide whether it’s yes or no yourself
60-100 YES (perhaps following the Innsmouth

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Rule, detailed later in this chapter
YES/NO under Horror and Immersion).
If your question is answered by
“Yes” or “No”, then you can begin SPECIFIC QUESTIONS
interacting with that now-resolved If you have a specific question that
question. So, if after asking “Is this needs answering, which cannot be
town currently peaceful,” with a framed as a yes/no question, then
make 1-4 rolls on the Verbs Table.
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likelihood of -20 due to there being
some unrest in the area, and I get a
“No” then I might go to the Verbs
Table (Chapter 6) to get more
The Verbs Table (Chapter 6) is a list
of 499 verbs that are generated
through dice rolls, which you can
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information about the situation. Or, loosely interpret to formulate an
I might ask more questions, such as answer.
“Is there a riot going on?” If I get a Another excellent resource in this
yes to that, then I might consider regard is contained in the Mythic
high-tailing it out of town so my GM Emulator (available on
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investigator doesn’t get caught up in Drivethru RPG). The Event

the violence. To summarise, you ask Meaning Tables in this product
a question, roll, then interact with provide a great way to generate
the results. random directions and ideas and are
well worth checking out.
MAYBE?
Sa

If your result is maybe, then there is SKILL ROLLS

some other condition that needs to be Not every question will be decided
fulfilled for the thing to happen (or with the Q/A mechanic. Sometimes
not happen, as the case may be), a skill roll will be required. For
perhaps an appropriate ability check example, you could use Q/A to
to overcome a relevant obstacle or answer the question “Can my
achieve a stated goal. Or, it could be investigator scale this cliff,” but that
that your question is not framed negates the characteristics and
quite correctly given the expertise of your character. Rather,

6
 make a Climb roll to determine the you can’t seem to reach a conclusion
answer. as to a particular aspect of your
Train yourself to pick up on the story.
different things that call for skill
rolls, and then make those rolls. This YOUR CREATIVITY
REQUIRED
develops your character and adds the
The great thing about a solo,
element of randomness to the story.
generative system is that its main
The skill descriptions (pp.57-79) in
purpose is to fire your own
the Keeper’s Rulebook will give you

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imagination. A system such as this
a good idea of what each skill
cannot provide every detail of your
covers.
scenario. You also, as pseudo-
Remember also to track successes to
Keeper, need to provide your own

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take advantage of possibly
input and interpretation to the
increasing your skill scores at the
answers, and occasionally fill story
end of part of a scenario, or at the
gaps here and there. No two
very end of the scenario itself. See
scenarios using this system can
p.94 of the Keeper’s Rulebook for
possibly be the same, as the person
more information on skill
making the rolls and answering the
improvement.
various questions will interpret the
JUST DECIDE
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Occasionally, your story will flow
smoother if you just decide that
results differently every time
depending on context.
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a certain turn of events takes
place. Remember, you as
Keeper of your own campaign

(Miskatonic Repository Art Pack - Ill Omens)

are in charge of the story, so if
you wish it to go in a certain

Note in a Book, by Marco Monte

direction, that’s your call. You
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might decide that your

character successfully follows
someone, without rolling
Stealth for it. Perhaps your
investigator is smart enough to
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know that stealth isn’t one of

their strong suits, so they keep
their distance but still follow
their mark to whatever location
they are headed for.
However, sometimes deciding is
not appropriate, especially when
a Skill roll might be called for.
“Just deciding” is for moments
when your story has stalled and

7
 KEEPER KNOWLEDGE THEATRE OF THE MIND
In solo campaigns, we must You should aim to use just your
necessarily play the role of both journal (an exercise book) this pdf,
Keeper and investigator, although printed out, and polyhedral dice
our roles are modified somewhat (usually the d100). That should
from a traditional game. We’ll call provide you with everything you
the Keeper role a pseudo-Keeper need and will remove the need for
role. You, although controlling your looking at screens - too much.
investigator, will at times have more Some appropriate atmospheric music

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knowledge of the mystery they are (my favourites are Altrusian Grace
facing, such as when you know what Media and Cryo Chamber) are also
Mythos creature they are facing but recommended to “set the tone” of

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they do not (unless they have in- your solo adventuring).
depth Mythos knowledge). In Theatre of the mind is essential.
situations like this, the intrigue Spend time envisioning, in detail,
comes from seeing how your what is happening in your
investigator reacts to and copes with campaign, the characters, the
those situations. But for the most locations, the horror. Freak yourself
part, this system is designed to out!
reveal clues (and the greater
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mystery) as the player moves
through the quest.
HORROR AND
IMMERSION
Naturally with a solo format, it is
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TABLES not so easy to feel the horror that a
The tables provided herein are skilful Keeper might generate.
designed to work in conjunction with Every effort has been made to try
the Q/A Mechanic in helping you to and create a system that unfolds the
generate another level of detail for story as your investigator moves
your solo scenario. through it, but consider the
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following guidelines as you go about

SETTING creating your solo scenario.
There are no real restrictions with
setting. I like the 1920s, and I ♦ Players must be invested in
sometimes like to set events in my feeling horror, otherwise it won't
own home town where I grew up. work.
Sa

This provides a bit of familiarity and ♦ Horror is removing safety

allows me to get more immersed in (someone, something, etc) from
the context. Of course, you could the player.
always choose good old Arkham, ♦ Horror forces players to make
Massachusetts if you want the pure morally questionable choices
authentic Lovecraftian experience. which ups the horror factor.
Players aren't just good heroes
killing the bad guy without
repercussions.

8
 ♦ Players should feel isolated from
help - either because help doesn't QUICK TABLE
REFERENCE
believe them or is not there when
they need it. Generate Generate
Pg Pg
♦ Players should feel a sense of a... a…
helplessness and despair from the
Auditory
conflict generated. 48 NPC 28
effect
THE INNSMOUTH RULE

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Random
We’ll create an optional rule here Clue 45 55
Event
called the Innsmouth Rule. This
states that, when choosing between Dangerous
25 Rumour 51

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different options for story occurrence
advancement (when you are
interpreting a Q/A roll, or when Information
14 Scenario 10
interpreting the Verbs Table), you source
should always choose the one that is
most perilous for your investigator. Story
Location 60 21
Please note, this rule is optional. Direction
However, it should up the ante for

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your scenario (if your ante has not
already been sufficiently upped!)
Monster 35
Visual
Effect
49
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DESCRIPTION
Just as is recommended in the core
books, try in your journal to describe
the action your investigator is
attempting before making rolls. This
will help you also to judge whether
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the roll should be regular, hard or

extreme.
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The Lesson, by Senecal

(CC BY 3.0)

9
 CHAPTER 2: GENERATE A
SCENARIO
GENERATING A SCENARIO
Here are some sample scenarios - fairly open-ended - to get your creative juices
flowing. If these are not to your taste, use the V e r b s t a b l e , R u m o u r s T a b l e ,
or one of the alternate methods listed later, to generate something new.

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d100 PROBLEM

1-2 Important relic or item lost. Book stolen?

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3-4 The town water supply has dried up and no-one knows why

Inhabitants of a town are becoming diseased / going mad / dying

5-6
mysteriously

Environmental disturbance /
7-8
Strange Weather / Infestation / Plague

9-10
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Investigator / notable figure left some time ago on a journey but has not
returned.
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11- You discover a map or rumours of a great mystery hitherto
12 undiscovered

13- A photographer claims to have captured an image of a being hitherto

14 never recorded before.
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15- You are passing through a town and notice that the locals are acting a
16 little too nicely towards you. Almost as if they don’t want you to leave.

Your most trusted friend gives you a package and implores you to take
17- it to such-and-such a person. He also tells you not to open said package,
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18 but tells you that his life, and the lives of thousands, depend on you
getting this package to its destination.

A convoy passes near your house, many military vehicles, and a large
19-
truck which has all the windows blacked out. What are they carrying in
20
there?

21-
An infamous item, said to be cursed, has surfaced and is causing havoc.
22

10