GUMSHOE PS -- a dice pool hack

GUMSHOE P.S. – a dice pool variant

I really like what Pelgrane Press is doing. They bring out some of the finest and freshest, well-written, lavishly creative and exciting material I've seen in years especially in their Trail of Cthulhu and Night’s Black Agents Gumshoe game lines.

Unfortunately, the players of my group don’t get to read these products so I must convey their urgent value as game master. And alas, sadly, my players either are passively unimpressed with Gumshoe’s house system or actively dislike it – and this is a complaint I’ve heard from other gamers too.

So, because I’m a fan of dice pool systems, I wrote this little mechanic to replace the Gumshoe d6+Ability system without requiring the players and game masters to change their character sheets, session prep notes or shed tears scribbling over their beautiful Pelgrane Press products.

I call this engine GUMSHOE P.S. The P is for pool and the S is for successes. You still have General and Investigative Abilities. If you GM lets you make spends for clues as per O.G. (original Gumshoe), then do so. But if you GM is just not comfortable describing success without rolling dice, then that’s just fine too.

The reference Kenneth Hite’s Night’s Black Agents for rules uses this formula: (NBA XX).

You decide how many dice you want to spend and roll them as a pool against the difficulty with four being the average. You add up the amount of rolled dice to equal or exceed the difficulty number and the remaining dice are the successes. You do not count the added-together dice as success points. You also add the successes together for a total success just in case there’s a match and one needs to take precedence over the other.

Apply modifiers to the success total to get your damage value.

If there’s a success total match on a contest match, the highest success total using the fewest successful dice takes precedence ¬– the respective order is the HIGHEST TOTAL with the FEWEST DICE.

Modifiers are simple: You add them to success total.

You can roll spent-dice pools with a zero die. You roll one die but you treat the 6 as a zero – because it looks like the tear of shame falling from your eye. Or like all the pips after the apple has been eaten and thrown away, depending on what die you choose to use.


  • This certainly makes it more complicated, to the extent that I don't really understand it. What's the issue that you have that you are trying to resolve?
  • I have found that player's struggle with the lack of dice rolling in GUMSHOE, especially with investigative abilities. I think it stems from them thinking that they can't do anything if they don't roll dice which is clearly not right, but it's a hard hurdle to get around after playing success based games for 30 years (in case of a couple of my players). So what ends up happening is that I over compensate and give too many clues away for free.

    I have thought about trying out a simple dice rolling for Investigative Abilities (1d6+Ability Pool vs. a Difficulty Number) to see if they find new clues as a way to help motivate them to look without me needing to coach them as much. But I have reservations, just like I reservations about your system above, because anything that complicates GUMSHOE goes against the spirit of the system. Though I understand your intent.

    At the end of the day though, if your players don't like GUMSHOE, I wouldn't change GUMSHOE but play another system and add the influences to that system. My Trail of Cthulhu campaign almost derailed because of a player hating the system, but thankfully, I had other players who were more open minded and are attempting to learn.
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