As befits a game with such a strong following, there’s no shortage of game advice for Call of Cthulhu. There’s a wealth of stuff in the Keeper’s Guide, and there’s some excellent advice in The Haunter of the Dark, a story-to-adventure how-to from Paul Baldowski for his own Cthulhu Hack system. Vaesen also has some excellent plot structure tips in its GM advice.

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All of these are relevant to the plethora of Call of Cthulhu-style games (Cthulhu Hack, Trail of Cthulhu, Cthulhu Dark, Delta Green, etc, etc), and more generally supernatural horror investigation games (Vaesen, Fear Itself, etc, etc). As always these may not be to your taste – let’s have some agreeable banter in the comments if that’s the case.

Use Safety Tools

As a minimum, stick an X card in it. Explain what it is, and what it does, and be prepared to act on it. More nuanced (and more complex) tools are available – use those if you’d rather. You have no idea what the triggers are for your players, especially at a convention, and even if you think you do, having one in place will reassure you and your players that you take their concerns seriously.

If you’ve tried it and not used it, that’s great – having it there means you have some confidence that your players were comfortable in the game. If you don’t care for comfort, and your plan is to shock your players for real, to get a reaction – well then you shouldn’t be running games at all, and certainly not at a convention. Get a grip.

Signpost Clues. Un-Signpost Un-Clues

If the NPC they meet in the coffee shop is important, make her sound and look important; give her quirks and mannerisms, and have her drop clues pointing to sources of information. Offer skill checks and even more clear signs: she nervously grasps her handbag, glancing down to the corner of a book kept within. Justin Alexander explains it better than me when he talks about the Three Clue Rule – have multiple ways to move the investigation forward, and be prepared to have some of them come to the players as well if they don’t get them. Keep the pace.

As important as this, if an aspect of the scene isn’t important, don’t describe in it exacting detail so that the players think it is. Don’t plan any red herrings. The players will come up with these anyway – let them theorize, and gently head them off and back to the core. If they ignore the NPC above and begin looking into the rare coffee beans they serve, just circle them back round to the plot as soon as you can. Having antagonists that are active can help with this – if an investigation is stymied, have the clues come to them – maybe carried by men with guns.

Start with an Actual Scene

By an “actual scene,” I mean an in-game event with an element of risk and/or choice. Not a mission briefing, not a mysterious party invite, not waking up in the morning. Start at the party, at the scene of the crime, at the location of the Shoggoth attack, looking at the smear of blood that was once the victim.

There are variations, of course – in Delta Green, you’re likely to want a mission briefing at the start – but try starting with their first encounter of the mission and covering the briefing in flashback – it’s not as if they have an option to take it or not (especially in a one-shot). In Vaesen, often you’ll begin with a letter inviting you to investigate – but you get to pick your Advantages for that adventure – start in the carriage or on the train to the site of the investigation, and do this in flashback.

In any case you want your first scene to telegraph the PCs in the direction of your plot, making it impossible to ignore – and hopefully give them enough to do that they don’t start too much theorizing until they’ve found out more.

Make Investigation Scenes Worthwhile

Investigation scenes should do one or two things – they should advance the plot, bringing the PCs closer to their ultimate adversary, or they should grant some advantage in that confrontation. “Advantage” is relative, of course – in Purist Cthulhu it might just be a good escape route.

By making investigation scenes reveal a weakness of the antagonist, a way in or out, or a key part of their backstory, you make these scenes valuable and keep the plot ticking along at pace. Scenes that look like investigation scenes, but reveal nothing and don’t move the plot forward, are just wasting everyone’s time. Flavour and atmosphere can be delivered during a useful scene, rather than being the focus of an entire scene.

Don’t Explain it Afterwards

Or rather, put it in the actual game. “What you didn’t find out was that…” is rubbish. Throw that information in, and resist the urge to gloat if the players haven’t solved your problems. Any reveal should take place in-game; not after it as a sort of “if you’d done better this would have happened.” Clever plots, NPCs and monsters are only clever if the players meet them.

So there you are – I’m indeed no expert on investigative or horror gaming, although I do know a thing or two about one-shots. You can also hear me and the Smart Party picking apart investigative games (specifically, the Vaesen introductory scenario) on their Youtube channel. What are your top tips for investigative gaming? Put them in the comments – or on twitter – and I’ll agree and/or argue with you about them!