# Dice pool game design woes

#### mamba

##### Hero
Does the attack pool have to be 1 to 6 dice? If it went up further (larger increments / start higher), that could solve your issue.

#### mamba

##### Hero
I'm trying to think of solutions to this before I jettison the whole thing and try something else. One is that maybe one of the sides on the attack dice is a critical success and counts as 2 successes? Or explodes? I've no idea how to calculate the odds for that though.
You can always brute-force it (one side as two successes)

 TARGET NUMBER -> 1 2 3 4 5 6 1 die 50% 16.67% 0% 0% 0% 0% 2 dice 75% 41.67% 13.89% 2.78% 0% 0% 3 dice 87.5% 62.5% 33.33% 12.96% 3.24% 0.46% 4 dice 93.75% 77.08% 52.08% 28.01% 11.50% 3.47% 5 dice 96.88% 86.46% 67.36% 44.21% 23.77% 10.24% 6 dice 98.44% 92.19% 78.65% 58.97% 37.85% 20.41%

Exploding dice have a lower probability than that, because instead of getting two points on a ‘6’, you get close to 1.6 points on average

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#### clearstream

##### (He, Him)
Can you introduce an element that allows the player to add dice to the pool? Perhaps a Push mechanic? Or Assistance from other players? Or situational methods like high ground or flanking or what have you?

This leaves your math unchanged and possibly opens up other avenues of design. Which may be good or bad, depending on your goals.
One version of that is you roll one or two additional dice, and if you use them to succeed you must narrate a complication.

##### Explorer
It's a feature not a problem. There solved it for you.

If they want to succeed they need to lower the TN some how, like taking extra time, or getting help.
Adding extra dice would be more intuitive than lowering the TN however. Such a limit and rule would also open other options up like being able to tempt a player with more dice to attempt something.

To be honest I think that issue is the least of the problems looking at that probability chart, it isn't at all intuitive.

Having a skill of 5 out of six seems really skillful, but if the TN is 3 which sounds low, you only have a 50% chance of success, it moves up to 4, and you are very likely to fail. People with Skill 3, barely have a chance to succeed as TN, even though both sound average.

Adding things like crits explode and stuff like that makes it even less intuitive to understand.
It's worse than that, it's counterintuitive.

Opposed rolls would probably be the best solution, with the additional benefit that a roll could still be considered successful even if it fails to generate any successes as long as it's larger than the opposing one. You can even treat such rolls as success with complications.

#### Morrus

##### Well, that was fun
Staff member
Yeah as a very very general rule of thumb rolling twice the number of dice than the target number gives you about a 50/50 chance. Very roughly. Dice pools are defintely one of the least intuitive mechanics when it comes to estimating your odds; I like them though as I enjoy adding and removing dice as modifiers, and throwing a handful of d6s is fun (fireball!) -- I've made quite a few dice pool games.

#### clearstream

##### (He, Him)
Yeah as a very very general rule of thumb rolling twice the number of dice than the target number gives you about a 50/50 chance. Very roughly. Dice pools are defintely one of the least intuitive mechanics when it comes to estimating your odds; I like them though as I enjoy adding and removing dice as modifiers, and throwing a handful of d6s is fun (fireball!) -- I've made quite a few dice pool games.
For me, they're at least as intuitive but less susceptible to calculation.

By intuitive I mean that I can easily intuit that if I throw one more die I have a better chance to succeed. It's hard to calculate by precisely how much.

This is partly semantic: I believe it wrong to mix intuition up with notions of scrutability, calculability or precision.

#### TaranTheWanderer

##### Legend
What if you added 1 (or 2 or whatever) extra d6(or a d8 or something) of a different colour? That dice has 'effects'. a 6 doubles successes (or lets you re-roll your pool or roll your pool twice or whatever), 2-5 does nothing or adds riders or whatever, and maybe a 1 gives you -1 success or something?

#### clearstream

##### (He, Him)
What if you added 1 (or 2 or whatever) extra d6(or a d8 or something) of a different colour? That dice has 'effects'. a 6 doubles successes (or lets you re-roll your pool or roll your pool twice or whatever), 2-5 does nothing or adds riders or whatever and maybe a 1 gives you -1 success or something?)
Some systems make a subset of your dice exploding dice, and the rest ordinary, using different colours. So that you could have

White d6s are ordinary
Red d6s explode
Black d6s require narrating a complication if you want to count them into your result

Dice pools can have all kinds of charming features!

#### pemerton

##### Legend
The probabilities for exploding dice aren't so formidable, as the most successes you can benefit from are six. So long as you stop rolling when you succeed, and the TN is 1-6, the maths is straightforward. I'm not great at explaining it, but I'll make the table in Excel. The assumption is that a die explodes on a 6, so that a 4-5 is one success, while a 6 is one success + a third of one success (i.e. another 4-5) + etc...) As I'm in transit I'll likely do it over the weekend.
Calculating the mean is a fairly straightforward infinite series, I think - at least that's how I've always done it. But calculating the odds of hitting a given target number seems a bit trickier.

#### Bagpuss

##### Legend
Opposed rolls would probably be the best solution, with the additional benefit that a roll could still be considered successful even if it fails to generate any successes as long as it's larger than the opposing one. You can even treat such rolls as success with complications.

The Spartacus Board game uses opposed rolls, you then match dice highest to lowest (defender winning ties), if the dice is unopposed you need to roll at least a 3 for it to count, but if it is opposed and they roll a 1 and you roll a 2, it is still a success.

#### Sacrosanct

##### Legend
Opposed rolls would probably be the best solution, with the additional benefit that a roll could still be considered successful even if it fails to generate any successes as long as it's larger than the opposing one. You can even treat such rolls as success with complications.
That's how I do it. And this discussion is one of the reasons I went that way
Yeah as a very very general rule of thumb rolling twice the number of dice than the target number gives you about a 50/50 chance. Very roughly. Dice pools are defintely one of the least intuitive mechanics when it comes to estimating your odds; I like them though as I enjoy adding and removing dice as modifiers, and throwing a handful of d6s is fun (fireball!) -- I've made quite a few dice pool games.
Dice pools are much harder to figure out the math and odds, but I think they are more fun at the table in actual play, as you attest. And faster. It's definitely a better system for people who struggle with remembering all modifiers, and when you're just comparing highest vs highest, it speeds up combat by a significant amount.

*Edit Here is the link to the work in progress version. This is not the whole rules, just what I plan on having in the SRD so it would eventually be public anyway. Go to page 22 for a description on how they work (I don't expect you or anyone to read the whole document unless you want to lol). Feel free to mine this for ideas.

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#### MatthewJHanson

##### Registered Ninja
Publisher
This sounds like a job for AnyDIce!

I think I made this function correctly: AnyDice

The above is for rolling two dice you can change the number of dice by changing "2d" right after "output". It assumes that there are three successful outcomes on a d6 (4-6) and one of those successful outcomes causes the die to explode (6).

I capped the number of explosions at 6, because it can't actually do infinite, and I figured 6 should be plenty.

#### clearstream

##### (He, Him)
This sounds like a job for AnyDIce!

I think I made this function correctly: AnyDice

The above is for rolling two dice you can change the number of dice by changing "2d" right after "output". It assumes that there are three successful outcomes on a d6 (4-6) and one of those successful outcomes causes the die to explode (6).

I capped the number of explosions at 6, because it can't actually do infinite, and I figured 6 should be plenty.
6 is expressly enough, because that's the highest TN!

#### Morrus

##### Well, that was fun
Staff member
This sounds like a job for AnyDIce!

I think I made this function correctly: AnyDice

The above is for rolling two dice you can change the number of dice by changing "2d" right after "output". It assumes that there are three successful outcomes on a d6 (4-6) and one of those successful outcomes causes the die to explode (6).

I capped the number of explosions at 6, because it can't actually do infinite, and I figured 6 should be plenty.
Oh, that's super helpful.

Is that for only one die can explode, or that any of them can?

I'm not sure I'm reading it right. If I'm reading it right, the table then looks like this:

 TARGET NUMBER -> 1 2 3 4 5 6 1 die 50% 25% 13% 6% 3% 2% 2 dice 75% 50% 32% 19% 11% 6% 3 dice 88% 69% 50% 34% 23% 14% 4 dice 94% 81% 66% 50% 36% 25% 5 dice 97% 89% 77% 64% 50% 38% 6 dice 98% 94% 86% 75% 62% 50%

#### MatthewJHanson

##### Registered Ninja
Publisher
Is that for only one die can explode, or that any of them can?
That's for any of them exploding.

#### Blue

##### Ravenous Bugblatter Beast of Traal
To flip the question around - why is the task resolution assuming a single roll of the dice pool?

Just like in some RPGs it's not a single roll to drop a foe, but a cumulative effort, having tough targets require cumulative effort even to attempt is not a bad thing.

And then you an get into interesting aspects of multiple rolls. Perhaps each roll pushes completion time up a track, so minutes becomes 10s of minutes becomes hours, etc. Is there an inherent cost to a roll, like an exhaustion pip or something? Perhaps you can only continue if you get at least one success.

#### Morrus

##### Well, that was fun
Staff member
Well that might have solved the problem! Thank you! I'll try this in the next playtest.

#### Blue

##### Ravenous Bugblatter Beast of Traal
Prince Valiant has a rule that if all the dice are successes, an additional success.
This makes a too-small-by-one pool twice as likely to succeed at a task than an just-enough-to-succeed pool.

TN 2. 1 die = 50% chance, 2 dice = 25%
TN 3. 2 dice = 25%, 3 dice = 12.5%
...

Basically, you are replacing a 50% success die with a guarenteed 100% success.

In other words, it would often make mechanical sense to have a less skilled character try something to improve the chance of success, if you know the TN going in.

#### Nutation

##### Explorer
It's a feature not a problem. There solved it for you.

If they want to succeed they need to lower the TN some how, like taking extra time, or getting help.
ICONS takes this approach. Sometimes the PCs are facing an opponent whose Coordination or other attribute is so high that victory is impossible. The PCs will have to try Combined Efforts or exploit a Quality (weakness) of the opponent. I've also seen this in systems where armor subtracts from damage. This comes up in superhero games, where a thug might have zero chance of shooting Superman with a gun. It could come up in other settings by designer intent.

#### Morrus

##### Well, that was fun
Staff member
To flip the question around - why is the task resolution assuming a single roll of the dice pool?
It's a fairly fast-paced starship skirmish game which might have lots of ships on the map. Speed is a design goal.

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