Common dice pool

[Bossy]

The bulk of the system I'm designing for a Space-Opera game is based on a dice-pool common to all PCs:

1) Resolution is classical: dX+skill > difficulty, nothing special here besides the fact that the dice type is not defined yet
2) There's a dice pool and a dice pit, at the start of the game the dice pool contains 5d6, 10d8, 5d12 and 1d20, the dice pit is empty
3) When an action has to be resolved, the player chooses a die from the pool and rolls as described in (1), when done the die goes to the pit
4) When the pool is empty, refill with all dice from the pit

For instance, say that Zorglub wants to dodge an asteroid, he has a skill-level of 2 in "Spacecraft", the difficulty is 8, so he has to roll 6 or more. His chances to succeed depend on the die:
   d6 -> 16.67%
   d8 -> 37.50%
   d12 -> 58.33%
   d20 -> 75.00%

In other words, a player chooses to increase or decrease his character's chances according to the die. Another way to put it is that the group decides if the current action should be favoured at the expense of future ones.
The figures (dice types and numbers) are not necessarily definitive, I will fine-tune it later in order to come with a balanced and practical start pool and difficulty scale. The goal of such a system is to use this resource management to encourage action anticipation and playing balance between PCs.

Any thoughts? Improvement ideas? Caveats?
Also I'm pretty sure I crossed an indie RPG with a common dice pool mechanic but I can't put my hands on it. Someone remember?

[Darcy Burgess]

Hi Bossy,

The "dice pit" dynamic sounds pretty keen.  The first big question I have for you is what aspect of Space Opera, as a genre, are you trying to reinforce with the dice pit?

Next, a comment; you may want to consider scaling the contents of the group pool based on the number of characters.  The flip side of this comment is, what happens to the decision making process if the group pool isn't scaled?

Oh!  You should probably check out John Wick's Thirty.  It uses a group pool in conjunction with individual pools.

Cheers,
D

[chance.thirteen]

I like the idea. It reproduces the main feature of a deck of cards or a bag of stones or whatever, in that once an item is used, it is out of play, and the possibilities for the future alre altered. This is my favored form of randomization, and the dice are a good dohicky on the table, and their effect on a given test resolution are knowable so its a decision for the group, which is also enjoyable. Any thoughts on who gets to decide which die can be used? Normally I would see this defaulting to the player, to test teamwork from individual to group, or consensus to test teamwork from group to individual, but I could see some value to restricting what dice can be taken without full consensus, which might represent characters doing supporting actions, or betting in game on this event at the expense of alter one.

I don't know if it would completely upset how you are seeing this playing out, but I will mention that some games include a mechanisms to reset before you have exhuasted all tokens/cards/dice. EG Deadlands used the Black Joker as the signal to refresh the deck. Maybe this has some use to you, maybe not.

[Bossy]

The first big question I have for you is what aspect of Space Opera, as a genre, are you trying to reinforce with the dice pit?

This is a damn good question I can't answer precisely, I just have bits of arguments.

Actually this mechanic was meant to fit the tone rather than the genre. I wanted something full of surprises, hence the single die roll rather than a sum of dice. I also wanted something that catalyzes those short moments of narrative tension: at the most critical moments of a scenario, either the players have kept higher dice, success is "guaranteed" and they feel the satisfaction of having played well, or they compromized their mission by spoiling their resources, they fail miserably and GM has a lot of improvization to do (which is nice, imo). In more dice consuming parts (read: fights), chances are that the pool will be refilled more than once. In this case the dice type differential will be a tactical tool, on which aspect does a group will put its efforts? Attack? Defense? Damage? Movment?

Another thing I hope for this mechanic is an incentive for players to talk with each other about what should be done. I noticed that there's always a couple of players who "take over" the game: if they are warriors everything in the scenario will eventually become a fight, if they're wizards everything will eventually become arcane, etc. This behaviour is probably unavoidable but may become an annoyance to other payers (including the GM). I thought that having a dice pool as a common resource would objectivize (and even penalize) this behaviour.

I see Space Opera (along with many cinematic genres) with quite specialized characters, each one has his glory/heroic moment where the mission success rests on his specialty. The dice pool/pit gives the chance to players to rekon and dispatch these moments.
Since nobody asked about what dice a GM should roll, I'll answer it would be awkward for the GM to have a pool and a pit for the whole set of NPCs. My idea would be that the GM rolls the dice of the type corresponding to the NPC significance in the scenario: pawns (stormtroopers) roll d6, more important characters (Lando) roll d8, bosses (Jabba) roll d12 and may even have access to a d20 (Vader).

Next, a comment; you may want to consider scaling the contents of the group pool based on the number of characters.

That was obviously under consideration, the most important thing is the balance between the dice type. Note that since the pool is regularly refilled, the total number of dice in the pool is just a matter of commodity: the less dice in the pool, the more often you have to refill it which can be a hassle in the middle of a game.

I also considered the following tweaks:
  - characters contribute to the pool differently (more d12 for veterans)
  - the d20 is still unique no matter how many players
  - reward groups during the game by adding higher dice in the pool

The flip side of this comment is, what happens to the decision making process if the group pool isn't scaled?

I never thought about it. As I saw things, the player chooses, period. Though it is more efficient for the group to anticipate actions and reach a consensus about the use of dice. I guess, each group will have its dynamics for the decision making process, so it would not be useful to legiferate about it in the rules.

I like the idea. It reproduces the main feature of a deck of cards

That's true. I never thought about it in this way. The main differences are:
  - players have full visibility on what is left, where it takes some memory effort with a deck of cards
  - dice are way more practical and faster to handle than cards

but I could see some value to restricting what dice can be taken without full consensus, which might represent characters doing supporting actions, or betting in game on this event at the expense of alter one.

As I said to Darcy, I'm reluctant to impose too many restrictions on the which dice a player can pick, the individual judgement and the group consensus must be the primary mechanisms. Though for the sake of balance supporting actions, as you mentioned, can be limited to the choice of the main character. Also, for fun, advantages and drawbacks can have an effect on the choice: a Perfectionist has to pick the highest available die, a Phobic has to pick the lowest available die in the appropriate situation, etc.
And, huh, I'm afraid I don't understand the betting part...

I don't know if it would completely upset how you are seeing this playing out, but I will mention that some games include a mechanisms to reset before you have exhuasted all tokens/cards/dice. EG Deadlands used the Black Joker as the signal to refresh the deck. Maybe this has some use to you, maybe not.

I remember Deadlands and, quite frankly, even if I fancied the whole system, I disliked the black joker: it did nothing for the PCs and you had to shuffle the game, it was a loss of time and it punished players (like myself) who counted cards.


Btw, thanks to both of you to consider my sketch of a mechanic.

[Vulpinoid]

  - dice are way more practical and faster to handle than cards

That's not entirely true, but I'm not writing to argue with you regarding that point.

What I'm writing is a suggestion to counteract he players who will always choose the high dice for themselves.

Consider this suggestion (using what you've already suggested as a base-line)...

The players and GM share a fluctuating pool of dice.

The total pool has a number of d6s equal to the number of players, a number of d8s equal to twice the number of players, a number of d12s equal to the number of players, and a single d20.

The pool begins evenly distributed between the GM and the players.

Every time a player uses one of the dice, it's passed over to the GMs part of the pool. Every time the GM uses a die, it's passed back to the players.

This way, if a player uses the d20, then the GM will have access to the d20 for a harder challenge later. If the players keep using the d6s, and the GM uses up their high dice making things challenging, then the GM will only have access to d6s for the remainder of the game.

Conversely, if the GM uses the d20 to make a particular challenge hard, then the players will get access to the d20 making one of their skill attempts easier later in the game (as soon as someone uses the d20, it gets passed back to the GM for another potentially difficult challenge).

In a situation like this, players might even ask to have a higher difficulty dice used just so they can gain access to one of these higher die types in the future.

Just an idea...

V 

[Bossy]

Just an idea...

Nice. It just made me think of the dK system which is a tweak on the d20 system. Players roll a d20 but they can add as many d6 they have at their disposal (called dK), however for each dK rolled, the GM adds one to the NPCs pool. Conversely.

So far this is the best mechanism I've read for this purpose. However I wish that remains optional. Indeed, if a GM really wants to penalize dice spoilers, he just has to wait for the last d12 to be used (shouldn't be long) and make the player roll for something important. The embarassment for being a failure, for jeopardazing the mission or for being responsible for more trouble should be enough.

[MacLeod]

I like the Common Dice Pool idea for sure.

I can imagine a few nifty moments...
Challenges require one to grab the highest die available.
Intimidation requires one to grab the lowest die available.
Special attacks that "freeze" the highest die available for a certain number of Rounds. Others may outright destroy dice, perhaps until the pool is refilled or maybe even permanently!

Perhaps a Gamble mechanic could be used... don't like the result? Roll another die from the pool and take that result instead.
Given the idea of a Gamble mixed in with those 'special attacks' I mentioned above... There could be a Reload Pool mechanic that penalizes the player's when they have to "Reload" the Pool. Perhaps timed unlock... the highest dice won't be available until a certain amount of time/Rounds pass.

Just a bunch of random ideas off the top of my head.

[Egonblaidd]

I like the idea, as someone that enjoys the economic aspect of strategy games this idea of resource management appeals to me.  As you said, it will also inspire teamwork among the players, and allow for high chances of success in what would normally be difficult situations provided the players manage the dice pool well, which will make for some nice, epic cinematic moments where the players pull off impossible stunts.

Almost as soon as I started reading V's comment I thought of more or less the same idea he did, that a die could be restored to the pool when the GM uses that die.  I wasn't thinking of it quite in terms of swapping between player and GM pools, more as the GM being able to use any die, but that die going into the players' pool afterwards.

Something you'll definitely want to consider is how dice are restored to the pool.  Are all dice restored once every one of them has been used?  Theoretically, the players could get two back-to-back d20 rolls this way, do you want to allow that?  Perhaps it would be better to restore dice in the order they were used, for example if the d12's were exhausted first then they would return to the pool once emptied, and the players would have to wait (perhaps until after the next test) before the next group of dice was restored.  Or maybe rather than restoring dice through use it would be better to use some sort of in-game event to restore dice, something like sleeping at an inn in fantasy RPGs.  What you want to consider is how players will make decisions based on the dice pool refill method.  Do you want them to save certain dice for last?  Do you want them to use certain dice first?  If a refill occurs in the middle of some sort of conflict (i.e. combat), how will that influence that conflict, or do you want refills to occur during conflicts at all?

One option might be to give the players an inexhaustible supply of some kind of weak die, maybe a d6 or d4, so that even when the pool is empty (pending a refill) they still have something to roll with.  If you did this, you would need to decide whether these "unlimited" dice could be used any time, or only when the pool was empty.  Obviously this mechanic would only make sense if the dice aren't restored as soon as the pool is empty.

[MacLeod]

I had a similar thought about an unlimited die... but instead of mentioning that, I went with the Reload Pool idea. While you have a limited number of D6s in the pool, as soon as you 'reload', the D6s unlock first... then D8, D10, D12 and finally D20. One character could sacrifice his turn to "charge up" or ready himself, effectively unlocking the next die type quicker. Something like that.
I would add D4s if I had that 12-sided die that lists 1 ~ 4 three times... but the Common Dice Pool would only have a very limited number of those.

Unless the GM is going to have his own personal Dice Pool... static TNs may be the best way to go. That, and exploding dice... limited to one additional roll. This would enhance the D4s usefulness but not make it very powerful when scaled against the other dice.

What sort of numbers are you looking at for outside of the die type? Too high and you risk making the lower die types useless without the ability to explode them. Too low and you risk making the higher die types too powerful... Perhaps instead of adding to the rolls, Skill ratings could determine what die type you are allowed to roll when making use of it? Any die greater than that costs something. Something like... Stamina, Hit Points, Flesh Wounds, Spiritual Points, Psychic Points, etc... You could throw the whole exploding dice bit out... do something like Savage Worlds and have a Wild Die that is based on Skill rating.

I'm going to cap off my random ramblings by mentioning that it would be cool to have a like in Don't Rest Your Head... as an optional rule, of course. Madness and Fatigue dice!

[greyorm]

I'm loving this system already.

Note: one of the problems we ran into with the card-based SAGA system (in internet time, that's back during the Ice Age of gaming, just after dinosaurs walked the earth) was players trying petty actions with no consequences just to get cards out of their hands and get to redraw. It seems to me that would be an issue that could arise here as well, with players trying petty, pointless actions ("I juggle, and I roll a d6! Aw, I failed, oh well.") in order to cycle into the pool's refresh phase. We didn't have a good solution to the problem, though we had a few hacks we developed.

In your situation, I believe Vulpinoid's fix would work quite well: there's an incentive NOT to hand the d20 or larger dice to the GM until absolutely necessary, even at the cost of one's own effectiveness, unless it is necessary to do so to survive/succeed, etc. That creates a nice bit of tension for player discussion: "Do we really need to succeed here? Can't we just withdraw and do this some other way?"

Also I'm pretty sure I crossed an indie RPG with a common dice pool mechanic but I can't put my hands on it. Someone remember?

ORX uses a common, (potentially) steadily increasing die pool that everyone at the table can dip into to use, in addition to whatever they have on their character sheet. Dice the players use go back into the pool, while dice the GM uses are discarded after rolling. This creates an incentive for the GM to use the dice up himself ASAP so the players can't use them (his task in the game is to kill the characters), though other rules create a balance of whether or not anyone really WANTS to use the dice, especially the big dice (for the GM). Something similar may work for your game.

[Bossy]

I'm happy to read so much positive input. I didn't expect that many replies actually. Thanks to all of you.
There are so many ideas; I'll try to bounce them.

I can imagine a few nifty moments...
[...]
Just a bunch of random ideas off the top of my head.

Indeed the fact that players have a choice opens a lot of possibilities. However I'm not too eager to put restrictions on this choice because in the end it could hinder the original goal of the common pool. I'm all for less rules and more GMing. If I'm good enough at writing and desining , I can make a consistent set of optional rules: GMs would select some of them according to their experience and confidence.

Something you'll definitely want to consider is how dice are restored to the pool. [...]

Here's an example of why The Forge/First Thoughts is a nice forum. Severeal posts made me realize need to think hard about the pool refill. The most difficult constraint I'm imposing to myself is: keep it simple. I still don't see a (balanced) mechanic that doesn't need to keep track of dice numbers/types on a paper or to maintain several stacks of dice around the table. I think that having a bowl full of dice and no other dice on the table may already be felt as a cumbersome constraint (for some players I know).

One option might be to give the players an inexhaustible supply of some kind of weak die, maybe a d6 or d4, so that even when the pool is empty (pending a refill) they still have something to roll with.  If you did this, you would need to decide whether these "unlimited" dice could be used any time, or only when the pool was empty.  Obviously this mechanic would only make sense if the dice aren't restored as soon as the pool is empty.

Default dice... Excellent idea!
I'm personally biased against d4.

Note: one of the problems we ran into with the card-based SAGA system (in internet time, that's back during the Ice Age of gaming, just after dinosaurs walked the earth) was players trying petty actions with no consequences just to get cards out of their hands and get to redraw. It seems to me that would be an issue that could arise here as well, with players trying petty, pointless actions ("I juggle, and I roll a d6! Aw, I failed, oh well.") in order to cycle into the pool's refresh phase. We didn't have a good solution to the problem, though we had a few hacks we developed.

Yeah. I remember a system (can't name it) where you could progress in one skill by failing rolls. That started with a sensible intention: you learn by mistake. However players couldn't stop themselves at rolling useless tests in order to gain skills... I believe this can be managed with appropriate GM response (at that time, I was too novice to do that): "so you fail your juggling... well, you just threw a ball on Saruman's face, now Saruman's quite angry at you...". A GM should never let players tell what is important and not or what is a petty action or not. Just my way of seeing RPG.
Btw, V's system would only reinforce such behaviour: not only petty actions would get rid of lower dice, but would also fill the GM pool with them...

What sort of numbers are you looking at for outside of the die type? Too high and you risk making the lower die types useless without the ability to explode them. Too low and you risk making the higher die types too powerful... Perhaps instead of adding to the rolls, Skill ratings could determine what die type you are allowed to roll when making use of it? Any die greater than that costs something. Something like... Stamina, Hit Points, Flesh Wounds, Spiritual Points, Psychic Points, etc... You could throw the whole exploding dice bit out... do something like Savage Worlds and have a Wild Die that is based on Skill rating.

Now it's time for probabilities, numbers, tables and computation. Yay! I initially chose d6, d8 and d12 because the respective probabilities of getting 5 or more have a nice property. If you look at the probability to get a target number for different die, you have:

target	d6	d8	d12
4	0.50	0.63	0.75
5	0.33	0.50	0.67
6	0.17	0.38	0.58

You will notice that the difference between d8 and d6 is roughly the same as between d12 and d8. So a medium target of [5 + medium skill level] would seem sensible. I was thinking of skill levels ranging from 0 to 4, or from 1 to 6 depending on the tone I want to give to action resolution, as you pointed out.
The actual problem is not really the balance of probabilities but the balance of maximum values. Half the values a d12 can yield are impossible to get with a d6: that's a challenge because, for some targets, a d6 cannot open the possibility of a success, that's frustrating. So I thought dice could be open-ended (reroll and add if you get max value), so you can get the same values with much lower chances.

What do you guys think if instead of [dX+Skill > Target], players roll [Skill dX > Target], à la White Wolf but variable target number? From the top of my head:
Pros: more choice for players, number of successes can be used to quantify success
Cons: needs more dice in the pool, steep probability curve

[MacLeod]

Static TNs and Opposed Rolls are always good... It really depends on how you intend on making things like Attributes and Skills/Abilities work. It has always made sense that Attributes have an effect on Skills. I'm not hip to the scene on how White Wolf games operate, after wading through all the fluff I came to realize that the game wasn't going to be a good fit for me so's I never properly learned of the game. @_@

I took the idea we have been discussing here and implemented it into a little variant I had already written... It isn't a complete system by any means. I like to think of it as a mix between Savage Worlds, Donjon, Starblazer Adventures, this Common Dice Pool idea and the Attribute concept someone had here on the Forge. The last idea being a minor detail at best. From my view point it looks like a fairly simple game on the surface with the potential for rich, crunchy, and tactical decisions. I can upload the rough draft if anyone is interested (the last two files I uploaded for this place haven't had any attention so I'm holding back this time).

[Castlin]

Another consideration: what if there are more than two sides in a conflict? How to split the pool then, and which side do dice go to when they're spent?

How about conflicts between players?

[MacLeod]

I know I'm not the OP but its all speculation at this point anyways...
Are you referring to multiple sets of player teams, or multiple teams of the opposition...? It makes a difference because the pool isn't used by opponents. I also think that all PCs would draw from the pool, regardless of affiliation, location or what have you. Even NPCs that would come along to help the PCs wouldn't draw from the pool, they would get a default die and have to deal with it.
I think a game using such a specialized mechanic would also have to be a focused sort of game, with a team work theme to avoid in-fighting. Perhaps some extremely potent, special bond that links the fate of each PC together. Even if that wasn't present, two players facing off drawing from the same pool could be interesting. Initiative would be pretty important!