Does a GM need more dice than a d2?

In the majority of RPGs that I've seen, the Game Master narrates what happens in the world, and what happens when PCs take actions. Sometimes, the GM doesn't know what happens, so the GM asks for a roll, or makes his own roll (unless, you know, Numenera, in which the GM doesn't roll).

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?

If one result has 75% odds of happening, I think most GMs can say, "this is easily more likely than not, so yes, it happens." Suppose those odds drop to 70%. Does the GM really need to roll a d20, or can she say that it's close enough to 50/50, and just flip a coin?

My next question stems from combat, when the GM is supposed to do a more significant amount of dice rolling. Is there an important difference between the BBEG hitting* PC1 at a 30% rate, PC2 at a 55% rate, and PC3 at an 80% rate, or (almost) never hitting PC1, flipping a coin for PC2, and always hitting PC3?

*Take this part with a grain of salt - I'm not a big fan of the hit/miss dichotomy.

A lot of older RPGs (or newer RPGs modeled on recreating older RPGs) utilize a simple pass/fail mechanic to resolve action and, yes, in those systems I'd say there is an argument to be made that the GM could employ a binary die without significantly impacting the play of the game. HOWEVER, many other (mostly newer) RPGs take into consideration degrees of success (and failure) when resolving action and, for those systems, a simple binary die wouldn't work at all.

jdrakeh said:

A lot of older RPGs (or newer RPGs modeled on recreating older RPGs) utilize a simple pass/fail mechanic to resolve action and, yes, in those systems I'd say there is an argument to be made that the GM could employ a binary die without significantly impacting the play of the game. HOWEVER, many other (mostly newer) RPGs take into consideration degrees of success (and failure) when resolving action and, for those systems, a simple binary die wouldn't work at all.

Click to expand...

This is right. Three categories of outcome with great utility for play are

• Success, you do the thing, it happens as planned
• Success with complication, you do the thing, but there's a hitch
• Failure with consequences, you don't do it and here's the cost or injury

Each changes the game state in a way that is productive.

D3 then? Probably not as the middle outcome is the one that should be most common. You then additionally want to consider how the chance can be interacted with (consider the meaning of +1 for a D3 system.)

GMMichael said:

If one result has 75% odds of happening, I think most GMs can say, "this is easily more likely than not, so yes, it happens." Suppose those odds drop to 70%. Does the GM really need to roll a d20, or can she say that it's close enough to 50/50, and just flip a coin?

Click to expand...

I read something in Dragon Magazine years ago, I think it was in a sage Advice column or a Dungeon Craft article, but I couldn't find it if I tried. Regardless, the writer said that as a DM they use d100% rolls at 50/50 to resolve many outcomes on their side of the screen. As a DM I have used this ever since and I find it works well if you're not overly concerned with answering anything more than determining success or failure. I use it a lot for NPCs that develop organically during play.

It all depends on how much granularity you want in a game. There are certainly games out there with mechanics that streamlined (and even more so -- Dread uses a Jenga tower!)

So you're right that a TTRPG doesn't need more granularity than a coin flip; it just comes down to what the players prefer. I personally enjoy more crunch than that.

GMMichael said:

If one result has 75% odds of happening, I think most GMs can say, "this is easily more likely than not, so yes, it happens." Suppose those odds drop to 70%. Does the GM really need to roll a d20, or can she say that it's close enough to 50/50, and just flip a coin?

Click to expand...

I have a way different, non-binary, view on outcomes... I'm quite fond of 4 outcome systems (CS, S, F, CF). I have whole heartedly embraced both FFG Star Wars and L5R flavors - the only reason I didn't like WFRP 3E was that the system was too focused upon cards + dice + markers.
Any one of the following will trigger a roll to see what happens...

• Game Rules call for a roll
• at least 10% odds of success¹
• At least 10% chance of failure¹
• some non-success/non-failure side effect of the roll²
• Quality of success or of failure matters
• Player states an interesting failure mode

I'll note as well: the PBTA mode of only 1 stated difficulty is a big negative for me.
I want at least 3 explicit and 5 total difficulties (Explicit; typically Easy, Moderate, Hard. Implicit: add Automatic and Impossible.)

Likewise, on dice...
Single die as primary mechanic? d10, d12, d16, d20, d30, d100
2dX as primary mechanic? I find 2d6, 2d8, 2d10, 2d12, 2d16, 2d20, 2d24, or 2d30 fine.
1dX+1dY: I prefer that the range have X= [d4, d6, d8. d10, d12]. and wouldn't object to adding d14, d16, d18, and d20; for Y, same range, but also no die. My second biggest issue with both Blade Runner and Twighlight: 2000 4E is that they only have 4 attribute levels [d6, d8, d10, d12]. T2K has skills run [none, d6, d8, d10, d12] while Blade Runner preview has d6 as unskilled.
I don't mind player facing rolls; that should be obvious from my running Talisman Adventures and recommending Buffy/Angel/Army Of Darkness, jointly: Unisystem Lite. But I much prefer TA over Unisystem Light specifically because I, as a GM, have things to roll, and while they don't include to-hits, they do include random encounters, NPC attack damages...

---

1: As a general rule, I set difficulties based upon the rubrics in the game; in Traveller, I'll allow a roll with as low as 3.333% fail - <3, or >11 is still a roll. In Pendragon, due to CS/S/F/CF outcomes, until auto-crit (skill + mods >39), most actions get a roll. Highest TN was an NPC... Lancelot critically inspired to Lancefor a total >80 after all the modifiers... But the PC was 24 base and also critically inspired. Didn't go well for either. Both died. In RuneQuest, 2% fail or 1% success.

---

2: Such as, in Talisman Adventures - Player had zero chance of success, but the roll has a only 4/6 chance of not having non-success non-failure side effects ... The kismet die on a 6 has a player boon, on a 1 has a GM boon. In the case last sunday, it was a called for roll in the adventure, so the player was rolling. They did get a 6... one other player, same situation, had to roll a nat 3 or nat 4 to fail, but rolled a nat 3... Fate point for me and failed roll.

I always found that the small chance outliers make the game memorable. When the PC doesn't stand a chance and stands to face the BBEG only to roll a critical twice and slay the monster and save the day. The orc in the 10x10ft room is not something we remember well. This is more player focused, but I recall some on the DMs side of the table where the lowly goblin needed a 20 to hit the paladin slaying all of his kin. Stepping up and slaying the paladin with a mighty blow before being muderhoboed by the rest of the PCs.

Well, it is like this for me the more the better. Players have all sort of crazy thoughts when they see a DM with a lot of dice in hand.

I think the metagaming and rules optimization is a lot of the fun for a lot of the people and lets them use excess math skills in an entertaining way.

Rolling funny dice is a part of the hobby, I think. The tactile sensation, the clatter on the table, the uncertainty...there's a reason dice games became so popular in saloons, etc. For whatever reason it's one of those things humans figured out how to amuse themselves with and it works.

Several of the ideas here are from a PC's point of view, and I appreciate the value of rules that allow PCs to optimize characters or to throw dice and tap into our pro-gambling genes...

But I'm mostly concerned with the GM. Unless the GM is loudly flipping a coin well above the height of the table/GM screen, would players really notice that GM rolls were being significantly simplified?* And given the effect of a random number generator on low amounts of numbers - say five-or-so attacks in five rounds - is there actually a significant difference in the GM's results if the GM just says: probably a hit, I should flip, or probably a miss? (I'm referring to the bell-curve effect of RNGs averaging over time/many rolls, and the chaos of few rolls.)

jdrakeh said:

. . . HOWEVER, many other (mostly newer) RPGs take into consideration degrees of success (and failure) when resolving action and, for those systems, a simple binary die wouldn't work at all.

Click to expand...

True, and we obviously can't put the square peg into the circular hole. Are some of these DoS systems beyond rule zero? Could a GM speed things up in these systems by rolling the d2 when needed, and letting the fiction or dramatic tension suggest when an additional degree of success is due?

*D&D nodded at this when it started providing average damage numbers for monster attacks.