This seems to be an age old debate. Which is better? Xd6 vs 1d20? Probabilities  seem to dominate this discussion and it's fair enough. I'd say the biggest advantages are how the probabilities of both options affect the system math. But I wanted to look at it from an aesthetics perspective. I realise this is completely subjective and everyone will speak from their own personal biases and that's fine because I want to hear the reasons. I'm working on a ruleset and I am completely torn on the issue and don't know which way to side to land on.

So which do you find more aesthetically pleasing? Have all rolls be a 1 or more d6 or have multiple dice types with the primary dice being 1d20.

Advantages of Polyhedral Dice
* All D&D fans (and fans of d20 derivatives) are more likely to give your game a chance.
* You can get more granularity with weapon damage rolls as they'll always be some multiple of polyhedral dice. E.g. With polyhedral dice one attack can hit 3 targets for 1d6 each (average is 10.5) while another attack can hit a single target for 2d10 total (average is 11).

Disadvantages of Polyhedral Dice
* Those gamers who hate d20 and refuse to play any games with it won't play your game.
* With new gamers I have seen it time and time again. They take a good session or two to learn which roll uses which dice and if they only play once a month it can take up to 6 months for them to learn it.
* Dice are more expensive for new gamers (which is why attacks that require lots of dice almost always require d6).

Advantages of Using d6s
* Those gamers who hate d20 are more likely to give your game a chance.
* A certain percentage of D&D gamers will be willing to play your game.
* Everyone (including D&D gamers) has some d6s lying around. If they don't it is significantly cheaper to buy a box of them vs enough polyhedral dice that you can always roll them at one time.
* Newbies will always know which type of dice to roll.

Disadvantages of Using d6s
* Those D&D gamers who refuse to play anything that isn't d20 based won't play your game.
* You're limited to damage rolls being separated by intervals of 1d6. You can have a modifier to the damage roll, but is that aesthetically pleasing?

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So what do people think? Is it aesthetically pleasing?

Talking a little about the probabilities. I'll get to damage rolls in another post as I want to run some numbers first. But with skill checks this is where 3d6 may shine.

2d6 Skill Roll
Unskilled (DC 5): Skill Rank 0
Amateur (DC 10): Skill Rank 5
Professional (DC 15): 10
Expert (DC 20):15
Unparralleled (DC 25): 20
Epic (DC 30): 25

All checks have a 72.22% chance of succeeding.

3d6 Skill Roll
Unskilled (DC 5): Skill Rank -2
Amateur (DC 10): Skill Rank 3
Professional (DC 15): 8
Expert (DC 20):13
Unparralleled (DC 25): 18
Epic (DC 30): 23

All checks have an 80% chance of succeeding.

1d20 Skill Roll
Unskilled (DC 5): Skill Rank 0
Amateur (DC 10): Skill Rank 5
Professional (DC 15): 10
Expert (DC 20):15
Unparralleled (DC 25): 20
Epic (DC 30): 25

All checks have a 80% chance of succeeding.

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Why is the lowest DC at DC 5 and then all subsequent categories add +5 to the DC? Because as a GM it's easier for me to remember that the number is going to be around 15 vs 22 or 23. As people we tend to find it easier to jump ahead by lots of 5. I've seen this in D&D 4th edition, Pathfinder and D&D 5th edition. Multiples of 5 are always easier for DMs (IMO).

So in this scenario 2d6 and 1d20 have the same bonuses, although in 2d6 you're 7.78% less likely to succeed. In a d20 game -1 to a skill check isn't really seen as that big a deal and that's how I'm seeing the difference.

The 3d6 roll is the least aesthetically pleasing because it's not in multiples of 5.

The biggest problem I have with the 1d20 roll is that a DC 25, 55% of the time. An expert is meant to be good, but an unparralleled is meant to represent a Babe Routh or Don Bradman. They're a "once in a generation" type of person. They're not meant to be something an expert can do half the time. A way around this is to increase the Unparralleled DC to DC 30 and give an unparralleled person the ability to roll 2d20 and take the best result. According to google this takes the person with a +20 bonus to the check from succeeding 55% of the time to 80% of the time. Mathematically it achieves EXACTLY what I want and reduces the expert's chances to a mere 5% chance of success. However we've skipped DC 25 as being a category and introduced a new mechanic (roll 2d20 and take the best) that has to be given to the player somehow. That decreases the aesthetic beauty of the 1d20 roll.

If we look at 2d6 then they can only get a roll of DC 25 roughly 8% of the time. This means an expert can rarely match an unparalleled person, but really the expert is the pinnacle of mundane human achievement (Heroic tier in D&D 4th ed terminology) while it gives the unparralleled character a 72.22% chance of success without needing to introduce any special mechancis or increasing the DC by +10 instead of +5.

To be perfectly honest I'm inclined to abandon the d20 mechanic in favour of a 2d6 mechanic at this stage. However I'm hesitant simply because d20 is such a well known brand and unifying identity. All d20 games share a lot in common amongst their fans.

What do people think? Are there reasons for going with Xd6 over polyhedral dice that I haven't considered? Are there even more reasons to want to abandon polyhedral dice in favour of d6 that I haven't considered? Which do you find most aesthetically pleasing and why?

I prefer using multiple dice on a core mechanic over any single die but particularly d20. Rolling two or three d6 is much less swingy than a single d20. You tend to get more consistent results with multiple dice.

With 3-D printing becoming more popular, I don't see the cost of dice being much of a problem a few years from now.

In fact, with 3-D printing we may see an explosion in funky dice.
It's very hard now to market a game that uses d7's or d30's just because these dice require expensive online orders to obtain. Within ten years though, we might expect your typical new gamer to have the means to print them.

I think there's three things here: d20 resolution, step dice resolution, and multiple D6. D&D happens to be a hybrid d20/'polyhedra' (step die) system - it switches from one resolution system to the other for damage.
A real D20 system would be something like True20, and a real 'polyhedra' system would be something like Savage Worlds or Cortex.

Quote from: Bloody Stupid Johnson;833631I think there's three things here: d20 resolution, step dice resolution, and multiple D6. D&D happens to be a hybrid d20/'polyhedra' (step die) system - it switches from one resolution system to the other for damage.
A real D20 system would be something like True20, and a real 'polyhedra' system would be something like Savage Worlds or Cortex.

I used to have d14's and d16's (bought a pound of game-science dice).

I think the only thing between us and a d20 step-die resolution mechanic is the absence of d18's.

I prefer bell curves over straight linear distributions, but any XdY is fine by me.  It doesn't have to specifically be Xd6.  Even more than that, I like pool systems where each die is evaluated individually instead of adding them all up.  For purposes of this discussion, I can see how they might also qualify as "XdY", since they involve rolling multiple dice.

System math aside, it's also just plain fun to roll a huge handful of dice every now and then.

Quote from: JohnLynch;833511This seems to be an age old debate. Which is better? Xd6 vs 1d20?

You forgot another major option: d100. I preferences for RPGs from favorite to least favorite go: d100, d20, 2d6, 3d6, dice pools, weird dice (d14, etc.), unique dice (Warhammer Fantasy 3rd edition, etc.).

Quote from: RandallS;833679You forgot another major option: d100. I preferences for RPGs from favorite to least favorite go: d100, d20, 2d6, 3d6, dice pools, weird dice (d14, etc.), unique dice (Warhammer Fantasy 3rd edition, etc.).

I noted that too.

I'd go with d100, xd6 totaled with a wild die, 2d6, (first three are pretty much a time) then, d20, 2d10, 3d6, then pretty much anything else before we get to jenga towers and other weird shit.

The importance of bell curve distribution in die rolls is consistently overrated; what matters far more is the range and variance (in a statistical sense) of results for any given situation (skill level vs difficulty) and a sense of how that changes when the situation changes.

E.g. If all that matters is rolling 11+ it doesn't matter if you're rolling 3d6 or 1d20.

From a purely aesthetic perspective I've observed that non-gamers are fascinated when they see weird dice. So that's a mark in favor.

Against: few types of dice roll as nicely as d6's. They either roll too little (d4, d8) or they don't stop (d12, d20). D10's roll nicely, though.

Quote from: Cave Bear;833667I used to have d14's and d16's (bought a pound of game-science dice).

I think the only thing between us and a d20 step-die resolution mechanic is the absence of d18's.

DCC sort of went there. I can't remember if it actually uses d18s, but I think the 'dice chain' in it goes up to at least d24.

I like 2D6 and D20. I played lots of "handful of D10s" games, but for speed of resolution one or two dice is best.

Quote from: Arminius;833716The importance of bell curve distribution in die rolls is consistently overrated; what matters far more is the range and variance (in a statistical sense) of results for any given situation (skill level vs difficulty) and a sense of how that changes when the situation changes.

E.g. If all that matters is rolling 11+ it doesn't matter if you're rolling 3d6 or 1d20.

Agreed as far as that goes.  However, if you have a +2 modifier on that roll, then it becomes significant whether your distribution is flat or curved.  If you have two characters rolling, one with a base 11+ and the other with a base 6+ and they both have a +2 modifier on that roll, then flat vs. curved distribution is much more significant.

I like bell curves in my dice because they make modifiers more significant in the mid-range or when moving towards the mid-range and less significant as they move things out to the extremes.  You can't really do that with a flat distribution unless you want to break out calculators or lookup tables every time someone makes a roll.

Yup, when modifiers to target numbers come into play, a nonlinear distribution of the dice result can give you diminishing returns if that's what you want.

Quote from: nDervish;833787I like bell curves in my dice because they make modifiers more significant in the mid-range or when moving towards the mid-range and less significant as they move things out to the extremes.

It depends on how you look at it - but isn't it the other way round?

If you need 11+ on 3d6 then that's a 50% chance of failure. A bonus of +2 reduces that failure to only 26%, so you've halved the chance of failure.

On the other hand, if you need only 9+ on 3d6 then that's a 26% chance of failure, and a bonus of +2 reduces that chance of failure to 9%.

If you need 7+ on 3d6 then that's 9% chance failure, and +2 reduces that to 2%.

So in the first case you've halved the chance of failure, in the second case you've reduced it to by two thirds, and in the third case reduced it by almost four fifths.

Quote from: JoeNuttall;835463It depends on how you look at it - but isn't it the other way round?

Yes to the first. No to the second.

It depends on whether you are looking at the change in percentile points or as a ratio. Using your examples.

QuoteIf you need 11+ on 3d6 then that's a 50% chance of failure. A bonus of +2 reduces that failure to only 26%, so you've halved the chance of failure.
The ratio of the change is (50-26)/50 or a 48% decrease, but the change in absolute percentiles is a decrease of 50%-26%=24% points.

On the other hand, if you need only 9+ on 3d6 then that's a 26% chance of failure, and a bonus of +2 reduces that chance of failure to 9%.
The ratio of the change is (26-9)/26 or a 65% decrease, but the change in absolute percentiles is only 26%-9%=17% points.

If you need 7+ on 3d6 then that's 9% chance failure, and +2 reduces that to 2%
The ratio of the change is (9-2)/9 or a 78% decrease, but the change in absolute percentiles is now only 7% points.

So while the ratio of change is increasing the change in the number of percentage points is decreasing from 24 -> 17 -> 7.