Well, in this case, mostly untested. 
Here’s a mechanic I improvised while running Trail of Cthulhu last night:
Mitigation Test:When making a mitigation test, instead of setting a difficulty number the Keeper sets a “worst case quantity”. The Investigator then resolves the test normally (spending points, adding them to their roll, and so forth), but the result of the test is subtracted from the worst case quantity to determine the actual outcome. (In some situations, you might choose to use multiples of the test of the result.)
Example: One of the investigators has been bitten by a Mythos creature and the creature’s poison is turning their flesh to stone. The team’s doctor decides the only way to save their life is to cut away the “infection”. The Keeper calls for a mitigation test using Medicine to determine how much damage the doctor deals to the victim/patient and sets the “worst case quantity” to 12 points of damage. The doctor’s player spends two points, rolls a 4, and manages to perform the procedure while only inflicting 6 points of Health damage (12 – 4 – 2 = 6).
Example: An orphanage is beginning to collapse. An Investigator is trying to rescue as many kids as possible before the building comes down completely. The Keeper calls for an Athletics mitigation test to determine how many kids survive and sets the “worst case quantity” to 6 dead kids. The player asks if he can spend Architecture points to assist (by judging which sections of the building are in most jeopardy) and the Keeper agrees. He spends 3 points and rolls a 2… He’s just not able to find Timmy before it’s too late.
Example: The player is trying to carve a forged copy of a stone tablet, but is under something of a time crunch to get it done. The Keeper sets a “worst case quantity” of 48 hours and calls for a Craft test. The Investigator gets a result of 6, which the Keeper multiplies by 5: It’ll take 48 – 30 = 18 hours to complete the duplicate tablet.
Thanks to Colleen Riley, Phil Henry, Tess Keen, and Sarah Holmberg for being my guinea pigs.
This is a nice, simple approach to scaling success in checks. I particularly like the orphanage example, which might make a terrible person.
To bring everyone in, I often use something similar with giving a round (or, for very complex challenges, multiple rounds) of actions and granting benefits based on the number of successful actions.
But I’ve never actually used it for mitigation like this. I’ll have to see if I can work it in.
Cheers!
Kinak
This is neat. But I thought you didn’t like GUMSHOE, Justin? I admit I really like it, but I also agreed with your points about “breadcrumb” structure. Mostly I just use a bunch more clues and give out lots of free ones but I was wondering how you like to run it, and if you’ve actually come around to liking the system, despite not liking the hype about scenario structure?
I’m currently prepping to run the truly epic ETERNAL LIES campaign by Will Hindmarch, Jeff Tidball, and Jeremy Keller and I’ve been running a couple of warm-up one-shots to get comfortable with the system.
The adventure advice in Trail of Cthulhu is considerably better than the stuff in the earlier GUMSHOE systems. (It also has an amazingly awesome method of presenting the Mythos by treating it as a catalog of mysterious possibilities instead of a catalog of cemented realities.)
I’m… unconvinced by the system.
As you note, I’ve talked about the system’s failure to achieve what it promises on the tin (“they’ll always find the clue!”) in the past. The failure isn’t really a huge problem in and of itself, but the problem I have is all the tack-on problems the “solution” creates while failing to actually solve anything.
For example, Trail of Cthulhu spends nearly half a page saying, “Wouldn’t it be great if we hadn’t modeled all social interactions with the auto-success clue-finding mechanics? That’s really awkward when you want to resolve a social conflict that isn’t about finding a clue. So… uh… I dunno. I guess let the PCs always auto-succeed in social conflicts. Or, uh… umm… I guess if you want a different outcome, just railroad ’em.”
And in actually running the system I was actually surprised to discover how much of a railroad machine it really feels like in practice. (I thought the railroad-y stuff was limited to the advice on adventure design.) Partly that’s the game taking the option of “maybe, let’s find out” off the table so that everything is completely dependent on my whim.
But it’s also stuff like combat: The 1d6 vs. difficulty 3 base test for NPCs attacking PCs has proven really problematic in the pregen scenarios I’ve been running. The balance of the game (and the longevity of the NPCs) doesn’t make it feel like I’m actually just playing the opposition and seeing how things work out; it feels like I’m deciding on any given turn whether or not I’m going to auto-hit my target. It doesn’t feel like playing a game; it feels like imposing my creative agenda. (And if I choose to just opt out, suddenly NPC skill ceases to matter.) A dodge rule might help; I was also playing with the idea of basing damage on margin of success instead of a separate 1d6 roll.
I’m also confused by a system that has really explicit mechanics for attacks at different ranges, but then lacks any sort of movement mechanic to govern those ranges. (I’m thinking about lifting the range-change mechanics from Numenera Something like: Point-Blank/Close can be traversed as part of another action. Close to Near or Near to Long is an action, but you can also make an Athletics test to go from Close to Long (or vice versa) in a single action.)
On the other hand, the point-spend mechanic seems to create a pleasant back-and-forth dynamic in actual play if you tell the players when spends are available. (Which is what Trail of Cthulhu, unlike earlier GUMSHOE games, tells you to do.) I also think that with a little more practice the structuring of NPC conversations around the use of specific abilities can provide an interesting improvisation structure for clue-gathering/interrogations.
And the Stability/Sanity mechanics are fantastic. (As are the metagame methods of playing out long-term madness.)
System stuff aside: There’s really no question that Pelgrane is producing some of the best (if not the best) scenario material in the industry right now. ETERNAL LIES is just flat-out fantastic and most of the smaller scenarios I’ve looked at have also knocked it out of the park.
Hi Justin,
Now that you have run your Eternal Lies campaign, has your opinion of the Trail of Cthulhu rules changed?
What changes, if any, did you make to the combat to remove the feeling of just imposing your creative agenda, or the movement during combat?