Does a GM need more dice than a d2?

[Thomas Shey]

I will point out that a D8 roll is easy enough to simulate that way, and there are games that use coarser resolution than that. Mind you, the D8 is already coarser than I'm comfortable with, but its not prohibitively undoable with coin flips (though I don't know why you'd want to do it that way).

I don't think that's what the OP is actually asking though; I suspect what they're actually asking is whether you need more than three states: impossible, automatic or 50/50. If so, I've already expressed my opinion on that.

 

[GrahamWills]

Two games that were cited often in a thread on simulationist games were Runequest and Rolemaster. I don't believe one could pull it off for those simulationist games. As an aside, I interpret 4e less as simulationist and more as gamist.

Agreed on 4E being more gamist. I ran RM for many years and, hmmm, I'm not sure I agree with you there though. There is a fair amount of randomness in the tables, and I think that would be the part that would be most noticeable. For combat, you'd get a lot of results that were A, B and C crits and higher crits would be rare. But apart from that, most of the complexity is player-facing. In a way, it's a bit similar to 13th Age that the "noticeable fun" comes from randomness of monster attacks.

In fact, RM might be kind of an interesting case where the players would rapidly notice that you weren't rolling d20, but the game might not suffer much. After all, rolling a 75 with a rapier is so radically different than 75 with a mace that it wouldn't be tedious for the players to know the GM had limited results. And, thinking back on my campaigns, unusual rolls were nearly always only memorable when players made them. The only exception I can recall is the mountain guide with +140 in climbing saying "you take my ring of falling; I don't really need it" and then proceeding to open end low and fall to his death. But apart from that? Can't think of anything.

 

[GrahamWills]

The problem with flipping a coin for everything is that there is no verisimilitude. Jumping over a puddle and jumping over the Atlantic Ocean are equally difficult and equally easy. So you immediately find that you have the need for more granular rules if you don't want your game to be absurd and potentially meaningless.

Trying to keep us on track; we're not talking about flipping a coin for everything. Here's the OP:

When it comes to a simple does-this-happen-or-not, the GM either knows or isn't sure. If the GM isn't sure, it's probably because the odds of one result or the other are very close to 50%. Why not just flip a coin to resolve it? Is more precision really necessary?

Your example as framed by the OP:

Jumping over a puddle: NPC succeeds
Jumping over the Atlantic: NPC fails

The question is: Does the GM need anything more granular than a coin toss to resolve any situation in which they are in doubt?

Being more specific: If the GM rounds everything below 15% (say) to 0% and everything above 85% to 100%, and everything in-between is treated as 50-50, what will break?

For me, I feel it will only really break when the system strongly needs to know the actual results off the dice. For 13th Age it's because so many opposition abilities are tied to the exact dice roll. For Rolemaster, it's because the critical system is so intrinsic to the experience. But for generic degre of success systems, I might argue that the variety of inputs that modify the roll create enough variability that the lack of granularity in randomness is compensated by the abundance of granularity in the simulation/gamist steps.

Essentially, if my orc is swinging with either a +5 or +15 to hit, translating coin flip into d20 language, then the effects of bard song, bless, flanking, height advantage, disadvantage, cover, vision, passion, heroes feast, icon dice bonus, assists, favored foe, tapped aspect, weapon proficiency, defensive posture, berserker fury, magic weapon, divine assistance, and actual offense and defense skills more than compensate for any lack of granularity in the randomness generator.

 

[Celebrim]

Your example as framed by the OP:

Jumping over a puddle: NPC succeeds
Jumping over the Atlantic: NPC fails

I condensed that first order house rules for "The Simplest RPG in the World" out of the discussion, but sure that's not anywhere I haven't gone before.

The question is: Does the GM need anything more granular than a coin toss to resolve any situation in which they are in doubt?

And I answer, "Yes." And one obvious reason is what D&D 5e calls advantage. If a Hero has a 50% chance of doing something, then a Hero that has that as a Shtick can't exist unless the Hero with that Shtick has a better than 50% chance of doing the same thing - say a 75% chance. Likewise, there are going to be plenty of times when you don't want to round that 75% chance up to 100% because it's interesting if the Hero can fail some of the time. And then, what if a normal Hero has some fictional positioning that gives them an advantage? Well, that probably also gives them a 75% chance of success. And, well, if that's true then the Hero with the Shtick that also gets the advantage maybe has an 87.5% chance of success - still not enough that we are happy to round to 100% most of the time - but more granular than the regular Hero in the same situation.

And we can continue on like that, noting that in many settings we may have several different levels of Hero. Hulk is stronger than Spiderman who is stronger than Captain America who is stronger than an athletic human who is stronger than an ordinary human. As we get the need to simulate these different sorts of Hero, perhaps having a 'Strong' attribute from 1-5, we get different sorts of needed granularity that is broken in verisimilitude to setting if we don't in some way model it.

This has nothing to do really with needing to know the results of the dice. This is just enough levels of granularity to simulate the sort of minimum complexity that is going to come up in any system that is trying to model a narrative.

Essentially, if my orc is swinging with either a +5 or +15 to hit, translating coin flip into d20 language, then the effects of bard song, bless, flanking, height advantage, disadvantage, cover, vision, passion, heroes feast, icon dice bonus, assists, favored foe, tapped aspect, weapon proficiency, defensive posture, berserker fury, magic weapon, divine assistance, and actual offense and defense skills more than compensate for any lack of granularity in the randomness generator.

While a system doesn't need to track fictional positioning that strongly, maybe all that translates to is adding or subtracting coins from our pile we get where we need a single success.

The real question for me becomes, if all these piles of coins are doing is turning out 50/50 or 75/25 chances of success, why don't we just throw one d20 or one d100 and that way we really know what the odds are with more clarity and a lot less process?

 

[clearstream]

Agreed on 4E being more gamist. I ran RM for many years and, hmmm, I'm not sure I agree with you there though. There is a fair amount of randomness in the tables, and I think that would be the part that would be most noticeable. For combat, you'd get a lot of results that were A, B and C crits and higher crits would be rare. But apart from that, most of the complexity is player-facing. In a way, it's a bit similar to 13th Age that the "noticeable fun" comes from randomness of monster attacks.

In fact, RM might be kind of an interesting case where the players would rapidly notice that you weren't rolling d20, but the game might not suffer much. After all, rolling a 75 with a rapier is so radically different than 75 with a mace that it wouldn't be tedious for the players to know the GM had limited results. And, thinking back on my campaigns, unusual rolls were nearly always only memorable when players made them. The only exception I can recall is the mountain guide with +140 in climbing saying "you take my ring of falling; I don't really need it" and then proceeding to open end low and fall to his death. But apart from that? Can't think of anything.

Pursuing this line of discussion may reveal a lacuna in the OP's framing. Their question can be understood to relate to an index, as @Thomas Shey summarises it - "three states: impossible, automatic or 50/50." That index could look like this -

• GM decides - automatic success
• Heads - success or perhaps as you suggest 15 (which might not be a success)
• Tails - fail or perhaps as you suggest 5 (which might not be a fail)
• GM decides - impossible

The OP reads in part "When it comes to a simple does-this-happen-or-not, the GM either knows or isn't sure. If the GM isn't sure, it's probably because the odds of one result or the other are very close to 50%. Why not just flip a coin to resolve it? Is more precision really necessary?" Arms Law doesn't ask simple does-this-happen-or-not questions in combat. For example, how do I split my OB/DB if the check is d2? How do I interpret my attack effect?

The lacuna then is that whether or not we use a d2 for simple does-this-happen-or-not questions in an RPG, other questions may emerge that we would like to answer, but that cannot be answered with a simple binary (or trinary, if we include GM-decides). I could for example, concede the OP's central premise - were I confronted with a simple binary then I could use a d2 - without accepting that all my questions even have simple binary answers. One could also observe that who gets to answer the question, and what constraints may be upon them, is also not addressed in grasping our RPG questions as simple binaries answered by GM (which of course isn't what the OP commits to, but worth noting I think.)

 

[GMMichael]

And we can continue on like that, noting that in many settings we may have several different levels of Hero. Hulk is stronger than Spiderman who is stronger than Captain .

I'm not sure that this requires a die with more sides so much as a GM who knows where to draw the strength-line. Can Spiderman or Captain stop the tank? No, but Hulk could. Can Captain punch through the brick wall? No, but Spidey might, and Hulk could do it by accident.

The real question for me becomes, if all these piles of coins are doing is turning out 50/50 or 75/25 chances of success, why don't we just throw one d20 or one d100 and that way we really know what the odds are with more clarity and a lot less process?

That's the side issue. Why use a d2? Because the GM forgot her dice. Because the d20 just rolled into the dog bowl. Because the scene is PERFECT, and the GM doesn't want to stop to look through the dice pile for the right die.

It occurs to me that several of the ideas here don't stand up well against Cypher System, in which the GM definitely doesn't have more than a d2. Does it have granularity? Yes. Degrees of success? Yes. A GM searching for dice and doing small amounts of arithmetic? No.

I like a GM to do some rolling because it can make PCs more hopeful: a 4 or 5 out of 20 isn't all bad for a PC if there's still a chance that the GM rolls lower. It's sort of like an anti-20 when the GM rolls a 1. Does that work for a GM's d2? Maybe... a 1 would lose to any PC roll over 10, while a 2 would win against any PC roll under 11, right?