My most important advice for GMs new to GUMSHOE is this:
- Whenever possible, ask the players "Do you have any relevant skills?" or "Would you like to spend a point of something for a breakthrough?", instead of "Does anyone have a point of Anthropology?"
Naming the skill, and phrasing it the "You need Skill X, does anyone have X?" way makes the game feel more stilted, and provides the appearance of railroading, even if there isn't any. It's a seemingly-minor presentation difference, but it has a fairly significant impact on the way it all comes off to the player.
Plus, by leaving it open for the players to pick the skill they think will work, it opens the door to the players coming up with something the GM hadn't even considered. If they have a cool idea for how to pump someone for information using First Aid, when the scenario called for Reassurance, everyone benefits from that improvisation.
In the case of the two-part scenario that John ran at Emerald City Game Feast recently, for the first session, he was using the "laundry list" approach, saying things like "Geology or Biology would be helpful here. Does anyone want to spend a point in them?" It was just okay, fun but not exceptional. In the second session, he was being more organic, less mechanical, and very flexible, and it really made the game come alive. I had great fun playing last night.
My best advice for people designing GUMSHOE modules is this:
- Go back through your work, looking for every situation that might come up that where a Stability test or a Sense Trouble roll might come up. In each such situation, determine the difficulty of those rolls, and then put that information in a really obvious sidebar that is impossible for the GM to miss.
The module he ran was The Black Drop, a Trail of Cthulhu adventure set in a remote location, with a multi-national cast of PCs. If you're interested in reading my feedback comments intended for the module's author, follow this link. It has a few spoilers, though, so is probably not a good read if you plan to play the module.