Diceless GMing in Gumshoe

A few weeks back I started running a short Gaean Reach campaign.  I’m still playing in a friend’s second Trail of Cthulhu game, and have previously run a Night’s Black Agents campaign and one-offs for Mutant City Blues.

From the above description, it’s no surprise that I am a fan of Robin D Laws’ Gumshoe system, the engine that powers all four of those games.  However, playing so much Gumshoe also means knowing it well enough to recognise its limitations.  Two potential problems of the system are:

1.  Players have no input when their characters are being attacked.  Their Athletics score sets a static Hit Threshold, which the GM has to roll against, but usually NPCs have big enough combat pools to make hitting a certain proposition.  After that, there’s nothing for players to do except mark as much injury as the GM tells them.  It’s true that in some iterations players have options to find cover and move evasively, but these are all options in YOUR turn – by the time you’re attacked, it’s too late.  And whilst that harshness makes combat tense (violence in Gumshoe is supposed to be a scary prospect), it can also be disempowering for players, especially if their character is killed as a consequence.

2.  GM book-keeping is a pain.  There’s also a lot for PCs to keep on top of – ability pools constantly fluctuate, and often you’re tracking several different abilities at once – but at least it’s only for one character, and can all be monitored from a single character sheet.  For GMs running several NPCs, each with their own ability pools, keeping track of them all is a nightmare.  Admittedly there are ways to streamline the process (“All the mafiya thugs spend 3 Shooting this round”), but that’s not always an option if, say, you have two guys who are Shooting, one who has to Drive after the PC fleeing with the briefcase, one who just got charged and is using Scuffling now, etc.

Whilst watching an example of play for Numenera recently, I was intrigued by the prospect of a GM who never rolls dice.  When the PC attacks, the players rolls to do so, but when the PC is attacked, the player rolls to defend themselves.  It’s a mechanic I’m familiar with from Powered by the Apocalypse games, though typically the nitty-gritty of combat is something those systems don’t bother with in as much detail.  It occurred to me that a diceless GM would be a natural fit for Gumshoe – it means the focus of their attention is on delivering core clues instead of planning their own strategies for an encounter, which keeps the investigation element of the system front and centre.  And it would also seem to be a solution to the two problems I’ve outlined above.  If NPCs don’t make dice rolls, then they don’t have ability pools to track either, and if players are rolling to avoid an attack, then they are making decisions about how much effort to expend avoiding damage as it happens.  In this system, if your character dies, it’s YOUR FAULT for not spending more points from your defensive pool.  Or possibly YOUR FAULT for spending too liberally from your defensive pool earlier.

It’s also a good match for Gumshoe because Gumshoe ALREADY prioritises player-focussed dice rolling, at least in some capacity.  If a PC sneaks up on an NPC, the player is directed to roll Infiltration.  If an NPC sneaks up on a PC, the player is directed to roll Sense Trouble.  It seems intuitive that a PC inflicting harm and a PC receiving harm would be handled in the same way.

With that in mind, here’s an attempt to modify the Gumshoe system to cut out GM rolls entirely.


The first major change is that PCs and NPCs have completely different stats.  No longer do NPCs have a sequence of ability ratings; instead, they have ability thresholds, which PCs have to roll against in order to affect them or avoid being affected by them.

(I’m using thresholds, as in Hit Threshold, rather than modifiers, as in Alertness/Stealth Modifier, because I really don’t understand why Gumshoe uses one convention for shooting NPCs and a different convention for sneaking up on them.  Since Alertness/Stealth rolls assume a default difficulty of 4, a modifier of +1 is essentially the same as a threshold of 5, and whilst the difficulty of an Alertness/Stealth check can vary, circumstantial modifiers can alter Hit Thresholds as well.  I’ve decided to be consistent.)

Thresholds are difficulty ratings for when PCs use abilities against that NPC.  When a PC tries to sneak up on someone, they roll Infiltration, with a difficulty equal to the NPC’s Surveillance threshold.  When a PC tries to shoot someone, they roll Shooting, with a difficulty equal to the NPC’s Athletics threshold.  When a PC tries to not be shot by someone, they roll Athletics, with a difficulty equal to the NPC’s Shooting threshold.

To use the Gaean Reach ability list as an example, NPCs would probably have seven different thresholds:

  • Shooting (used when players roll Athletics to not be shot)
  • Scuffling (used when players roll Athletics to not be stabbed)
  • Athletics (used when players roll Shooting or Scuffling to shoot or stab, or when players roll Athletics to escape or pursue)
  • Health (used when players roll to inflict damage – see below)
  • Vehicles (used when players roll Vehicles in a chase, or possibly when players roll Shooting to blow up a vehicle)
  • Surveillance (used when players roll Filch or Infiltration to do something sneaky)
  • Infiltration (used when players roll Surveillance to not be surprised)

Because NPC ability thresholds are essentially just difficulty ratings, the usual Gumshoe advice on how to assign difficulties applies when statting out NPCs.  So 2 is poor, 4 is average, and 8 is exceptionally dangerous.  (This whole system is unplaytested, so I don’t know how well these values will model the dynamic of fights in Gumshoe currently, but it’s a start.)


In addition to their own ability thresholds, NPCs should be assigned a damage threshold for each of their weapons: claws 4, shotgun 6, etc.  When a PC is hit with a weapon, they immediately make a Health roll – the difficulty of remaining conscious is equal to the weapon’s damage threshold.

PCs can spend from their Health pool as normal to boost their Health roll.  Under this system, Health works the same as any other general ability – it can’t go lower than zero, and having a low Health score doesn’t necessarily mean you’ve suffered a lot of injuries (although it might).  It’s theoretically possible to keep passing Health rolls and soaking hits after your Health pool is reduced to zero, but it’s not particularly likely…

The first time you fail a Health roll, you may choose to be Hurt.  Whilst you’re Hurt, all difficulties increase by 1 and you can’t make spends on investigative abilities.  If you take another hit this fight though, you’re unconscious.

Some weapons are characterised as “lethal” – this includes swords, guns and many supernatural attacks.  If you’re hit by a lethal weapon, and fail a Health roll that would usually knock you unconscious, the effects are much worse.  You’re not just unconscious, you’re bleeding to death, and you need medical attention very soon.  Some armour can negate the effects of lethal weaponry; your GM can counter this with called shots (which reduces the NPC’s Shooting/Scuffling threshold) or bigger weapons (like a grenade launcher).


When you hit an NPC with an attack, roll to inflict damage with that weapon as normal.  If you match or exceed the NPC’s Health threshold, they are taken out.  Otherwise they grit their teeth and keep on going.  Mooks can be expected to have very low Health thresholds.

(The usual damage ratings of weapons in Gumshoe might need to be tinkered with here.)

Truly formidable enemies, coloquially known as “level bosses”, can choose to be Hurt the first time an attack exceeds their Health threshold – this reduces all their thresholds by one.  A second attack that exceeds their Health threshold will take them out.  If you really want to emphasise the fragility of mooks, then any mooks who are hit with an attack but don’t suffer enough damage to meet their Health thresholds can be marked as Hurt as well, and a second hit of any kind will take them out.


PCs can use the Medic ability to revive an unconscious ally.  Typically the difficulty for this is 4, but circumstantial modifiers may apply.  If the ally was taken out by lethal damage, then a successful Medic roll will stabilise them, but they’re marked as Hurt upon awakening.

Characters are Hurt until they get proper medical attention, at a hospital or a safe house at the very least.  In non-desperate circumstances, players attacked by non-lethal weaponry might well choose to be knocked unconscious by their first failed Health roll – sometimes being taken out by the one-hit-KO and waking up a short while later is less crippling than carrying the Hurt condition for the rest of the session.

In a Diceless-GM Gumshoe game, Health is just another general ability, and is refreshed in exactly the same way.  However, players can also use the Medic ability to restore lost Health points.  To do so, choose how many Health points you would like to try and recover: this is the difficulty of your test.  Restoring your own lost Health points with Medic increases the difficulty by 2.  A success restores the number of Health points you attempted to recover, a failure restores nothing.  Either way, you can’t attempt to use Medic again on that patient until they get to a hospital or refresh their Health pool naturally.


I’m happy with the system I’ve outlined above, and believe it addresses some of the problems I have with Gumshoe.  However, I’m well aware that it has issues of its own.

For one thing, it requires that every weapon in the game has two damage ratings – one for when it’s hurting PCs, and one for when it’s hurting NPCs.  I don’t think this is a huge problem – it’s just a single number for the former, and a D6 modifier for the latter.

Having completely different stats for PCs and NPCs might make the game harder to learn for new GMs.  However, Gumshoe as it stands doesn’t use exact mirror profiles for PCs and NPCs, as indicated above with the Awareness/Stealth modifer example.

The fact that NPCs don’t have a reducing Health pool anymore means that it’s impossible to chip away at a bad guy’s hit points over time.  This means that players can score a great hit, fail to meet the NPC’s Health threshold, and accomplish nothing whatsoever.  As potentially disempowering as this can be, I’ve never found “death by a thousand cuts” to be a particularly satisfying way to kill major NPCs, and the removal of diminishing Health was a deliberate feature to cut down GM book-keeping as much as possible.  Besides, an NPC with a dwindling Health pool was never actually disadvantaged in Gumshoe classic, they were just a little bit closer to death (at least until you Hurt them).  Keeping mook Health thresholds low, and using the optional rules for Hurting mooks that are hit but not killed, at least partially addresses this problem.

Finally, it’s clear that this is only the starting point, and that loads of the supporting rules in Gumshoe would have to be rewritten to accommodate its changes.  Contest rules – where players and GMs take it turns rolling, and the first one to fail a roll loses the contest – are one example of a mechanic that doesn’t work anymore, and Night’s Black Agents uses this as the basis of its whole Thriller Chase subsystem.  Similarly, many superpowers in Mutant City Blues involve rolling against an NPC’s mental defence, and in fact, I’ve now idea how NPC mutant abilities would be powered under the new system.  For me, this is exciting new material to cover (maybe in future blog posts!).  I think the central core of this revised edition is sound, and that the rest of the mechanics around it can be easily altered to slot into the new foundation.

Moreover, there are a number of things I like about the system above that don’t relate to my original design goals.  I enjoyed altering the rules for Health and Medic, to make them consistent with other general abilities, for example.  I don’t have a problem with Gumshoe using different rules for investigative and general abilities – that’s smart design that shines a light on how investigation in Gumshoe is special – but different general abilities using completely different rules has always irked me.  Hopefully I will get a chance to playtest this, and see if it works out as well in practice as it does inside my head.

5 thoughts on “Diceless GMing in Gumshoe

  1. I’m not all that familiar with Gumshoe. I played in that one Mutant City Blues game, which was fun enough that I want to play more Gumshoe at some point. But your suggestions here sound sensible to me as a layperson. I’m happy to be a guinea pig if you want to test this at some point.


  2. This will require the PCs to have more starting points for General Abilities – at least in the combat-related ones. You might need a parallel Health ability since it makes sense for players to raise it higher for spends.


  3. Why so? Don’t PC pools for Shooting/Weapons/Scuffling work in the same way as they do at the moment, rolling against a static difficulty?

    Not quite sure what you mean by a parallel Health ability, any chance you could elaborate?


  4. I like this idea. I tried a more player facing combat system in a recent Night’s Black Agents game. It worked ok, but not as great as I had hoped. The disappointment was primarily because I did not make enough changes. The game was at a convention, so I wanted to stay fairly close to the rules as written. Next time, RAW go out the window. I’d like to see Pelgrane release a new edition of Gumshoe that really seeks to be player facing. A lot of the ideas you have written above seem to fill that bill.


  5. Laws/Hite/Rogers did hint at their Dragonmeet panel that they were working on an update to Gumshoe, but so far all we know about it is that it will try and involve investigative abilities (and the things you’ve discovered with them already) more directly in combat. Very early days, too soon to guess what else will be included, but we’ll see.


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