Prepping an Old-School Call of Cthulhu Scenario

As a dad, software engineer, husband, and grad student, the amount of time I have to make my own adventures is sadly limited. I'm currently in my last class so I'm hoping the fall will bring more time both for this blog and for me to prep my own adventures. However, for the time being I've gotten great mileage out of pre-made scenarios.

One nice thing about Call of Cthulhu is there are a lot of such scenario out there. I especially like that there are a lot of scenarios suitable for one or two sessions of play - I love long campaigns, but right now such a style isn't quite suitable for me. It is also nice that you can take an scenario written for the old editions of the game and use it with the newest ones without any difficulty.

One thing in most Call of Cthulhu scenarios favor is they don't typically force a certain course of action for the investigators. I've had sessions where I'm pretty certain the author would barely recognize his or her scenario. Typically, Call of Cthulhu scenarios present the current situation, a hook, a bunch of locations, and a bunch of NPCs and monsters.

However, one challenge I've found, especially with older scenarios, is it is often a bit of detective work for the keeper to understand all the pieces. Over the years I've developed a bit of an informal system for prepping my scenarios. I usually have them in PDF format so I pull them into Acrobat on my iPad Pro where I can mark the up.

What am I looking for? Typically I want to make certain I understand:

• What do the investigators need to do to have a chance to succeed? 
• Who are the NPCs and how are they connected? Are there any potential allies?
• What will happen if the investigators do nothing?
• Are there any adjustments to make to my campaign? For example, any NPCs from previous adventures to reuse? Any changes needed due to our game taking place in a different year?
• Are there any aspects of it that show great potential for wiping out the investigators? This isn't to say I'll change it - but at the very least I want to make certain I'm aware of it if possible.
• What course are the investigators likely to take?
• Are there any easy to miss clues or discoveries? Are any of them vital?

That last bullet point is a biggie, especially in older scenarios. Indeed, it is the main reason that the game Trail of Cthulhu was created. Call of Cthulhu is a dangerous game and I think it is at its most enjoyable when success is not guaranteed - but I don't want to penalize players if they ignore, for example, a bartender, who turns out to be the only source of a vital clue. Again, that's not to say that failure should be impossible - but I do prefer there being more than one path to success. So I might tweak scenarios, either on the fly or during prep time, to have additional ways of getting required information. It's a balancing act - I don't want to play a game where every bit of information is fed to the investigators.

I may have made this sound a bit more "scientific" than it really is. But perhaps the greatest tool I have for this prep work is a pen and something to write on, whether physical or virtual. The odds of my players taking the "expected" course tends to be low - which I greatly enjoy. But I'm best able to give that freedom when I better understand the scenario we are playing.