Are Dice Pools Good, Actually?

I think that dice pools with successes work best with custom dice that can have multiple successes, penalties, weird effect, etc (look at the new L5R RPG for an example). The advantage of counting rolled dice is in a system that uses exploding dice, where you always have a chance, no matter how small.
 

pemerton

Legend
Most of what I'm playing these days involves dice pools of some sort or other.

Classic Traveller is mostly rolls of 2d6. Sometimes 3d6. The addition is easy. The smaller spread of results on 2d6 makes ties more common, and I like ties (when used with Let it Ride, to force the conflict onto a different field of endeavour).

Prince Valiant officially (ie as per the book) uses coins, with heads as success and tails as failure. This is the same as rolling dice labelled 0 and 1 and adding, I guess, but in our group we mostly use standard d6s and count successes - most of use are "evens" but our most diehard Burning Wheel fan is 4+. There is nothing "weird" about it that I've noticed, nor has anyone in our group complained. Pool sizes range from 1 or 2 to 15+ when a strong knight is jousting in heavy armour on a mighty steed in defence of lover or honour..

Burning Wheel is pools of d6s, generally similar in size to Prince Valiant. Normally 4+ is required but under peculiar circumstances it can be 3+ or even 2+. I have a set of charts that lists the probabilities for a given size of pool against a given obstacle.

What I like about the Prince Valiant and Burning Wheel pools is that (1) ties are more common, and (2) there is always a chance of failure when the dice are rolled. (BW is explicitly "say 'yes' or roll the dice", and Prince Valian works on a similar ethos.) This isn't something that you get with target number systems.

The most baroque dice pool system our group plays is Marvel Heroic/Cortex+ Heroic - the dice can be of all different sizes from d4 to d12, and the default is to add 2 to get the result to determine success against a target number, and then a third die determines the effect but based purely on its size, not its result. I haven't tried to create any probability charts for this as the maths would be above my pay grade!

The only system I play where the pool is rolled and you just keep the best die is Cthulhu Dark. By default there are no target numbers, only degrees of effectiveness of outcome. But sometimes an opposed die is rolled that sets the target number for success.

I think there are challenges in a roll and add vs target number system similar to those in a single die system like D&D or RQ, namely, that if the system allows lots of modifiers then if the maths is not carefully worked out success or failure can become automatic. Classic Traveller avoids this problem (in my experience) by keeping modifiers small. Rolemaster avoids it by having a mixture of auto-fails and open-ended rolls - the latter making it a dice pool system where the number of dice is randomly determined. I don't think the issue was all that well throught through in AD&D design, and I gather it can be a problem in 3E D&D as well. In 4e D&D I only encountered it at one point in one build - the Sage of Ages epic destiny.
 

pemerton

Legend
The advantage of counting rolled dice is in a system that uses exploding dice, where you always have a chance, no matter how small.
You can get this in Burning Wheel if you spend a player-side resource (fate point). Prince Valiant, on the other hand, has a hard cap (full successes is +1 success, but not exploding).

But you can do "always have a chance" in an addition-based system too, like Rolemaster. In two decades of play we saw some wild results (double- and triple-open-ended) that saved the day.
 

Bedrockgames

Adventurer
That being said, there are also disadvantages:
  • Most people don't know the probabilities for success for dice pools by heart; this gets tremendously worse, if you combine dice pools with variable success thresholds
I think this is both an advantage and a disadvantage. I kind of like the muddiness on the player side. Most people don't know the actual probability of their success of jumping over a ravine (they just have a general sense of their chances). I think that translates well in play. On the GM side it is more complicated because it can result in the GM not really grasping how difficult he or she just made a challenge. Again though, I think as long as the general feel of the probability is there, it is still good.
 

schneeland

Explorer
@Bedrockgames:
That's a fair point and a good observation. My feeling is, though, that most players (including me) will not develop a solid feeling for their chances of success, if there are too many variables (pool size, target number, no. of successes), so you're better off picking only one of them.
And of course, on the GM side, actual numbers are more important (as you already noted).
 

lordabdul

Explorer
It's funny to me that people talk about not having a clear idea of one's chances of success when, in my experience, the vast majority of D&D DMs I've seen in action would not tell the players what DC they're shooting for.

If you worry about making chances of success clear to the players, there's one and only one resolution system that's totally unbeatable: percentile systems. Roll D100 under your stat. Your percentage of success is right there on the character sheet.

Anyway, I like dice pools. They're fun, and you can do funky things with them.
  1. You can easily get a multi-level success system, because it's easier to count the dice than to do a subtraction to figure out a margin of success/failure.
    1. This might give you "bumps" in success levels, say from moderate success to complete success to critical success (although you need a GM that can translate that to a satisfying narrative consequence)
    2. Most commonly it gives you extra stuff like extra actions, which is very easy to grok and GM... for instance 7th Sea does that, each success is an extra action you can perform in the action scene.
  2. You can have weird resolution systems like trying to match dice for instance. Godlike/Wild Talents does that, and that gives you 2 measures out of the dice roll (the "width" and "height" of the match, like, say, 2 tens vs. 3 fours). I love to see designers explore other resolution systems like these, it shows that innovation isn't totally dead when it comes to rolling dice.
Dice pools have limitations though. I find that they lack granularity, and don't scale very well up and down. As such, they tend to be effective (IMHO) mostly in narrative-inclined games where it's less about wargaming and more about storytelling -- like, famously, the Storyteller system or the 7th Sea system. I don't think these games would have the appeal and "style" that they have without a dice pools.
 

Wulffolk

Explorer
I agree with many of @lordabdul points.

I really love the nuance possible with dice pools. I love that you can modify so many aspects of a dice pool, such as: type of dice, number of dice, difficulty target, number of successes needed, immediate action vs extended actions, etc.

Some of this can be done with a d20, but I prefer the consistency of a dice pool's bell curve over the wild variability of a d20.
 

Bedrockgames

Adventurer
@Bedrockgames:
That's a fair point and a good observation. My feeling is, though, that most players (including me) will not develop a solid feeling for their chances of success, if there are too many variables (pool size, target number, no. of successes), so you're better off picking only one of them.
And of course, on the GM side, actual numbers are more important (as you already noted).
They don't need a solid feeling in my opinion, just a general sense. There is a difference. I like the muddiness because the players are not running numbers in their head, they are going off the GM description and just know something like (I have three 3d10 in this skill so I am pretty good). Real people don't run numbers in their heads when deciding to dart in front of a car, or leap over a ravine. Having a shifting TN makes it easier for the GM to set the difficulty appropriately.
 

schneeland

Explorer
They don't need a solid feeling in my opinion, just a general sense.
...
I guess it comes down to preference here. At least half of my players tend to dislike systems where they don't have one (it's less of a problem for the people who lean towards the narrative side).
 

Ovinomancer

No flips for you!
They don't need a solid feeling in my opinion, just a general sense. There is a difference. I like the muddiness because the players are not running numbers in their head, they are going off the GM description and just know something like (I have three 3d10 in this skill so I am pretty good). Real people don't run numbers in their heads when deciding to dart in front of a car, or leap over a ravine. Having a shifting TN makes it easier for the GM to set the difficulty appropriately.
Sure they do. I mean, there aren't TNs in real life, but there's a constant evaluation of risk versus capability. It's fundamental to existence. Not having a way to gauge risk in games is bad. Your example of 3d10 being pretty good is exactly what's being discussed -- this knowledge isn't helpful at all if you don't know the level of the challenge. If it's a really hard challenge, but you don't know it, then your faith in 3d10 will lead you to make a choice that's not desirable. TNs aren't magic, they're how you, as GM, can communicate difficulty to the player based on what their PC's perceive.

Now, I prefer less number centric descriptions, so when I run 5e, for instance, I'll say things like, "It looks like an easy climb," or, "that sounds like a really hard thing to do, are you sure?" My players know that easy is 10 (or nearabouts) and really hard is a 25 because I uses the easy/moderate/hard/very hard/near impossible scale for 10/15/20/25/30.
 
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Bedrockgames

Adventurer
Sure they do. I mean, there aren't TNs in real life, but there's a constant evaluation of risk versus capability. It's fundamental to existence. Not having a way to gauge risk in games is bad. Your example of 3d10 being pretty good is exactly what's being discussed -- this knowledge isn't helpful at all if you don't know the level of the challenge. If it's a really hard challenge, but you don't know it, then your faith in 3d10 will lead you to make a choice that's not desirable. TNs aren't magic, they're how you, as GM, can communicate difficulty to the player based on what their PC's perceive.

Now, I prefer less number centric descriptions, so when I run 5e, for instance, I'll say things like, "It looks like an easy climb," or, "that sounds like a really hard thing to do, are you sure?" My players know that easy is 10 (or nearabouts) and really hard is a 25 because I uses the easy/moderate/hard/very hard/near impossible scale for 10/15/20/25/30.
But our understanding of the actual risks when we do things is no where near the precision of knowing the probabilities. Nor is it as precise as the difficulty descriptions in 5E. It is a very general, vague, and often inaccurate sense. If you try to punch me in real life, you have very little idea of your chances of successfully hitting me. You just have vague general sense and a general confidence level. Humans are not computers.

That said, players do need a clear understanding of what they are up against. They don't need the odds, but they need a visible picture of the challenge (there is a big difference between a 5 foot chasm and a 40 foot chasm).

But even in a dice pool system, part of the GM's job, if the game uses TNs, is assigning ones that make sense. That isn't terribly difficult to do. Even if the GM doesn't know the actual probabilities, they learn through experience what is difficult and what isn't. The challenge being faced, and the TN for it should match. But it doesn't need to be tailored to the PCs skill level. If they have a good dice pool, and are skilled at the task, they will have an easier time succeeding. If they have a bad one, and a not very skilled, they will have a harder time succeeding.

Personally I don't want players thinking in terms of numbers. In your example, they are still doing that because, as you point out, they equate the different difficulty levels, with a number. What I would rather give them is as good a description I can of whatever it is they are facing. I view the difficulty descriptions as guidelines for the GM, in setting the difficulty, not as guidelines for the players in determining whether they try something.
 

Bedrockgames

Adventurer
I guess it comes down to preference here. At least half of my players tend to dislike systems where they don't have one (it's less of a problem for the people who lean towards the narrative side).
It is definitely a matter of preference. If players want a clearer sense of the probability, that is fine. There is nothing wrong with different preferences. But also I think people sometimes get closed minded about mechanics. Like I said, I just like the muddiness and see it as a feature rather than a bug. There is nothing objectively better about dice pools, just like there is nothing objectively better than 1d20+modifier. They serve different functions. Ideally though I think people should be more open minded about different game mechanics. I play a lot of different games, and grew up playing lots of different games. D&D was always the go to for most people (it was just easy to get a session of D&D going), but we would frequently play games like West End's Star Wars, TORG, GURPS, VAMPIRE, etc). I never found shifting from one system to another particularly jarring. While I might find specific uses of dice not well thought out in a given game, I never understood being against a type of resolution system. You can take any type of dice system and find things to complain about on a forum. But my experience is generally that forum complaints don't match what I see as much at the table.

Regarding narrative play, I don't think it has all that much to do with that. There may be some styles where the muddiness would get in the way. But I am not particularly narrative in my approach, have more of a sandbox style. But I do lean on theater of the mind, rather than use things like miniatures.
 

schneeland

Explorer
@Bedrockgames :
Not contradicting you on being open to other resolution systems, but
  1. the same people didn't have any issue with d100 (Rolemaster/HARP) or 2d6 (PbtA) - so I feel it's somehow related to being able to assess easily how well you do on average
  2. I feel there has been shift to dice pools with fixed target numbers (cWod -> nWoD/CoD, Shadowrun 4+, Year Zero, I think also FFG Star Wars and Genesys)
 

Bedrockgames

Adventurer
@Bedrockgames :

  1. I feel there has been shift to dice pools with fixed target numbers (cWod -> nWoD/CoD, Shadowrun 4+, Year Zero, I think also FFG Star Wars and Genesys)
Some games do. And that is fine. However it doesn't mean it is the right approach for me (or the best approach in general). I prefer being able to shift the TN in a dice pool. My biggest issues with Dice Pools, is things like the buckets of dice problem that can arise, or the dice themselves getting bogged down in things like counting and canceling successes (so I avoid both of those in my own games). And I like to do a soft cap of 6d10 (and a hard cap of 10d10 for exceptional cases; and prefer to do take the single highest roll and compare to TN). But even then, I am sure there are people who like throwing handfuls of dice and the latter as well. I prioritize fast resolution though, because I don't like things like combat taking too long. Others won't prioritize that. I will happily play a game that does these things, however, if it is an otherwise enjoyable game and setting.
 

Bedrockgames

Adventurer
@Bedrockgames :
Not contradicting you on being open to other resolution systems, but
  1. the same people didn't have any issue with d100 (Rolemaster/HARP) or 2d6 (PbtA) - so I feel it's somehow related to being able to assess easily how well you do on average
I don't doubt peoples' preferences are grounded in something real. I am just pointing out those preferences are not universal (I don't really value being able to pin a probability on a given roll---especially on the player end). That said I do like the d100 system. I am also saying, I think on forums people tend to take a very hard line about these sorts of preferences that you just don't see as much at regular tables (and I personally wouldn't want to take such a hard line that I missed out on different types of RPG experiences). It used to be quite common to try out different systems all the time. I have this sense (and it could be wrong) that that changed during the d20 boom. Things are not as homogenous as they were during the boom, but there still does seem to be a lingering hesitancy to play different types of systems freely.
 

3catcircus

Adventurer
I prefer a dice pool approach. D20 roll below target number (TN being the attribute that controls the skill you are using). Sufficient skill ranks allow you to roll additional dice in your pool. The amount you roll below (or above) is your margin of success or failure. Each additional success adds 2 points to your margin of success. For combat skills, weapon damage is a fixed amount, modified by your margin of success.
 
I’m not sure I buy the idea that “count successes” is simpler than “count numbers”, unless the game always has the same numbers be success (eg, success is 5 or 6)
I can't stand variable success numbers in a dice pool - there aren't many people good enough to work out those probabilities in their head.

and honestly I just can’t like a system where I fail a task because I only succeeded twice, and needed to do 3 times. And yes, that still bugs me even a dozen sessions into a campaign in such a system.
Some successes should always do something noticeable.

so, what’s up with dice pools? Why is the bell curve not worth the trivial additional math? Is there something else about it that I’m missing?
First dice pools always have something approximating a bell curve - it's a binomial distribution and then we start tangling with the central limit theorem so we're getting close to a bell curve and get closer the more dice we add. That's an advantage of dice pools.

In addition handfuls of dice are fun to roll - and very fast to evaluate compared to either multiple modifiers and additions or double digit addition. You only need to cancel (which is an advantage shared by Fate despite 4dF not being meaningfully different from 2d6 in other ways (technically it's 4d3-8)).

There's also the fact that, especially with dice pools with multiple sizes of dice it feels a lot better to throw a bonus dice into the dice pool which might or might not do anything to represent an advantage than it does to give them a modifier which will automatically be more math and will always lead to a higher result.

That said, the only dice pools I genuinely like are those used in Cortex Plus, or Fantasy Flight's Star Wars or WFRP3e (or arguably Blades in the Dark) which use the dice pool to separate how successful someone is from whether there are also unwanted consequences.
 

pemerton

Legend
Some successes should always do something noticeable.
I would say that if you're rolling the dice there should probably be something meaningful at stake. But I don't think the actual number of successes rolled needs to be relevant beyond success or failure. Anymore than it normally matters, in D&D, whether you missed your target number by 3 or by 7.
 

Bedrockgames

Adventurer
I would say that if you're rolling the dice there should probably be something meaningful at stake. But I don't think the actual number of successes rolled needs to be relevant beyond success or failure. Anymore than it normally matters, in D&D, whether you missed your target number by 3 or by 7.
I have a general principle I live by as a GM, which is: characters don't need to roll to make coffee, unless they are being shot at or brewing a cup for royalty.
 

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