I intend to start a "Trail of Cthulhu" adventure or campaign, but I would like for the players not to initially know what they are going to be up against. So I would like to present it as a normal investigation or action adventure, and the Mythos aspects should only appear gradually.

Taking into account the fact that my players are not stupid and know something about Cthulhu Mythos (at the very least, from such boardgames as "Arkham Horror"), have you any suggestions? I should probably avoid classical New England-ish locations, for instance.

Are there published (or unpublished!) adventures suitable to such a project? Do you have any ides about how to "hide" specific aspects of the game such as Sanity scores (for instance, I could keep them for myself until later in the game)? Any other tips?

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    \$\begingroup\$ PoV not answer; Personally, I would not. Players can end up creating characters that they really hate if their assumptions about the world are change. I have also found in the past that some players hate Bate and Switch campaigns. Be upfront with hints about what might happen. I the best horror stories make you suspect that there is something to worry about long before telling you what it is. \$\endgroup\$ Jun 6, 2011 at 10:06
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    \$\begingroup\$ We did a Cthulhu adventure in Star Wars once. It was quite fun and the effects of the adventure added something to the rest of the campaign. \$\endgroup\$
    – user2015
    Jun 6, 2011 at 14:23
  • \$\begingroup\$ When you do something like this, really make sure (for example by knowing them and their loved and hated types of play very well) that you can assume beyond reasonable doubt that they will be up for it. \$\endgroup\$
    – Anaphory
    Aug 21, 2015 at 19:47

4 Answers 4


First of all, start with a different game (system.) Using anything Lovecraftian (CoC, ToC) would be a dead giveaway. Pick a (very) easy, generic system, preferably something your players are not familiar with. You'll want to tell them you read an interesting review about it someplace and would want to give it a few shots, to freshen up your gaming.

Previous to announcing this, watch (or just pick an already seen) movie or TV series (or computer game) that deals with the 1920s era (roughly) and that you're familiar with - and that has no obvious link to the Mythos. (HBO's Boardwalk Empire or LA Noire would be good choices these days.)

Now, tell your players about both the interesting new indie game and the movie/game you're so enthralled with nowadays. Prepare them for a story set in the vein of the movie/game. (Go for crime and investigation, that's an easy one indeed. Do borrow from your source.) Never refer to Lovecraft or Cthulhu. If your players bring them up, try not to confirm their suspicion.

Have your first few stories be really not about the Mythos. On the contrary: use red herrings. Throw a rare few Lovecraftian adjectives and descriptions about NPCs ("smells constantly of fish", "slightly protruding eyes" etc), use a few conspicuous props (strange paintings, a suspicious house) - but always present logical explanations for these. (The fish-smelling guy really does work as a fish-seller, the eyes are a medical condition explained away by a doctor whom the party trusts, the paintings are the works of a poor drug-addict artist, the house is architecturally unstable and is demolished during the story etc.)

Then, after two or three short stories (but still using the new system), start revealing the true nature of your campaign. Switch to ToC only when you've had the first real Mythos encounter/event.

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    \$\begingroup\$ Might I offer that you could use the CoC system, by using Chaosium's "Basic Roleplaying" and leaving out the sanity track? It's pretty good system on its own, and wouldn't be a dead giveaway, and would allow for easy transition to CoC (adding sanity) later on. \$\endgroup\$
    – Cthos
    Jun 5, 2011 at 16:57
  • \$\begingroup\$ That's an excellent idea, I think. :) \$\endgroup\$
    – OpaCitiZen
    Jun 6, 2011 at 5:26
  • \$\begingroup\$ or use Gurps but don't tell them you've got this link printed out: sjgames.com/gurps/Roleplayer/Roleplayer22/CoCToGURPS.html \$\endgroup\$
    – gbjbaanb
    Jun 6, 2011 at 18:39

Start by changing the period and the location. Classic Cthulhu periods are the 1890s, 1920s and 1930s (for Trail), so avoid those. Try an Edwardian, Regency, Elizabethan or 1950s adventure, for example. And, as you suggest, keep out of New England.

With Trail, you could easily keep Sanity and Cthulhu Mythos to yourself, until the Investigators see something Mythos-related. However, specific skills, such as Library Use, might make the players realise they're playing Cthulhu.

What I'd actually do is: use another GUMSHOE system, then graft Sanity and Cthulhu Mythos onto it when you need them. Try Fear Itself, which is designed for modern horror (it's billed as a slasher horror games, but ignore that: it works well for gritty urban horror). Start with a Fear Itself game, then slide slowly into Cthulhu. (Alternatively, for a military game, start with The Esoterrorists. For a SF game, start with Ashen Stars).

As for published adventures: look at The Final Case, a Fear Itself adventure which appears in The Book Of Unremitting Horror. Or try The Dance In The Blood (which I wrote) or The Black Drop, which are Trail of Cthulhu adventures that gradually induct the players into the horror.

  • \$\begingroup\$ I am sorry I can "accept" one answer only: this (and other ones) were almost as good. Congratulations on your published adventures, which look very interesting! \$\endgroup\$
    – DaG
    Jun 6, 2011 at 17:25

I ran a Serenity game with a Cthulhu basis, and I ran it like @OpaCitiZen said. The first four or five adventures had almost nothing to do with the Lovecraft mythos -- only one of them dealt with the Lovecraftian monsters, and only one character actually saw anything odd. Be patient, and have the first few adventures be traditional crime, ghost story, or gang wars.

One thing that works in your favor is once you set up the genre up as a "mystery" or "sci-fi", the players will use that mindset. Call of Cthulhu tends to do the "players are weak", so make sure the players really feel that they are in charge of their destiny.


Depending on how complex you may want your system, my group has had lots of success with GURPS. There are built-in rules for Fright Checks and the consequences of failure, and the system is adaptable to any setting. Considering how generic it is, there won't be any indication of what is coming.

As for the specific adventures themselves, they'll need to be adapted to the setting, which is the hardest part of this particular option. There are quite a few sites out there, but I don't have any specific recommendations - I'll talk to my GM later and see what we can put together for you.

  • \$\begingroup\$ Yeah I was thinking gurps can do anything, if my collection of Japanese RPG replay books have anything to say about the subject. \$\endgroup\$
    – Claytonian
    Jun 6, 2011 at 12:30
  • \$\begingroup\$ It would be a very good idea in itself, and I myself am a GURPS aficionado, but in this occasion I am specifically interested in trying out the Gumshoe system, the basis of Trail of Cthulhu \$\endgroup\$
    – DaG
    Jun 6, 2011 at 17:22

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