Bigger Heroes for Small GUMSHOE Groups

By John-Michelle O’Shea

In this article, I’d like to share some house rules for GUMSHOE designed to increase the chances of success for your characters. Why would you want this? 

Well, I can offer you several reasons why I do it.

First, there’s group size. I’m lucky enough to have had a regular gaming group for over thirty years. There are faces that come and go over time, old friends who crop up for sporadic remote play. But for the most part, we play in a small group of a GM and one to two players. 

The catch with playing in a small group like this is that published material frequently assumes more bums on seats than we actually have. The TTRPG industry was built at its earliest foundations on an assumption of around six players at the gaming table. This assumption no doubt suits club and convention play well enough, but I suspect very few home gaming groups have this many players regularly involved. 

Which leaves the small-group GM having to do extra prep or even wholesale rewrites of prewritten material to make scenarios work. 

One option is, of course, to scale down opposition. But this can be very unsatisfactory. Large climactic battles turn into sparse, depopulated scuffles. 

Another option is to add NPC allies for the party and then use that as the narrative excuse to negate opposing elements of the scenario and leave the players to deal with more curated elements of a scene’s threat. Again, this often feels unsatisfactory.

The second reason I offer can be described in two ways depending on your opinion. We are making success easier, and as our heroes can now do more in this easy mode, we are increasing the level of relative heroism in the scenario.

Is this more heroic or just ‘easy mode’? There’s no correct answer; I think it’s largely a matter of taste. But it also requires some care unless your group wants to remove all risk and treat a scenario like a 1980s action movie where Stallone or Schwarzenegger strides through every scene with the outcome largely guaranteed. The catch with this, of course, is that without a chance of failure, without risk, the sense of reward in a scenario’s conclusion is equally reduced. 

So, here is our hack for GUMSHOE as presented in Night’s Black Agents, Trail of Cthulhu, and Swords of the Serpentine. 

For all general ability rolls, player characters and major NPCs roll 2d6 and keep the best die instead of rolling 1d6 straight. 

Advantage gives an additional die for a roll of 3d6, keeping the single best. 

Disadvantage removes a die, taking the roll back to 1d6.

Mooks always roll 1d6; they never gain advantage or suffer disadvantage.

Complications now only happen on a roll of all 1s. 

Now let’s discuss these changes in more depth.

For all general ability rolls, player characters and major NPCs roll 2d6 and keep the best die instead of rolling 1d6 straight. 

This shifts the success probabilities for PCs and named NPCs as follows:

Difficulty	1d6	2d6
2	83.3%	97.2%
3	66.7%	88.9%
4	50%	75%
5	33.3%	55.6%
6	16.7%	30.6%

Straight away, just by switching to the 2d6 ‘roll and keep’ mechanic, you should find your characters’ pools now achieve more and last longer.

However, note how the increase in probability peaks on rolling a 4 and then reduces again when needing a 6. The element of risk remains, and the GM using this system doesn’t need to spike difficulties to balance it. Indeed, regularly doing so quickly negates it. It’s also worth stressing that we are not touching GUMSHOE’s health and damage mechanisms here either, so no character is going to become an unstoppable one-man army from these changes. 

We then introduce an advantage/disadvantage mechanism. 

Advantage gives an additional die for a roll of 3d6, keeping the single best. 

Disadvantage removes a die, taking the roll back to 1d6.

This change to the dice-rolling mechanism only applies to player characters and named, major non-player characters, not mooks. 

Mooks always roll 1d6; they never gain advantage or suffer disadvantage.

Granting advantage shifts the success probabilities for PCs and named NPCs as follows:

Difficulty	1d6	2d6	3d6
2	83.3%	97.2%	99.5%
3	66.7%	88.9%	96.3%
4	50%	75%	87.5%
5	33.3%	55.6%	70.4%
6	16.7%	30.6%	42.1%

The granting of advantage to take a roll to 3d6 is a major boon and should be treated with care. Advantage should never be simply situational; the GUMSHOE rules already cover situational modifiers. Advantage should be a narrative tool: the reward for your players taking time to plan and describe how their characters are prepping and planning to gain that advantage over their opponents. It should require effort to achieve and never be guaranteed. For example, players might well take all night planning a perfect ambush for enemies they believe to be mobsters, but have no idea that the enemy in fact has a supernatural element that nullifies their efforts. Indeed, they may in fact find that the tables are tipped to such an extent that they now have disadvantage. By increasing the stakes at either end, the whole scene has gained a new element of mechanical drama to accentuate the narrative; that is the real value of the mechanic.

We also change the frequency of complications. 

Complications now only happen on a roll of all 1s. 

This makes a complication much less likely in a situation with advantage: around 0.5% rather than around 16%, and only around 3% on our standard 2d6 roll.

This ‘rule of 1s‘ is pleasantly elegant; of course, it’s still possible to succeed by rolling a 1 and spending from a pool. So we aren’t saying a 1 is always a fumble, but the premise is that complications are rarer and, as such, are treated as more serious or special. 

Lastly, we don’t apply complications to mooks’ rolls; we aren’t interested in their actions in the same way. They are mooks, after all.

That’s it! Mechanically simple changes that allow a small group to achieve more and fight bigger foes without removing all sense of risk. Silly as it may sound, we also find it’s a much nicer tactile experience at the table. There’s now a satisfying rattle of dice with every roll that is oddly missing when rolling a single die.

I hope you find these changes as enjoyable as our group has, whatever your group size!