d20 vs. 3d6 "dice heresy" by Chris Sims

[thewok]

You get to spend 40% of that time as a failure. Good on ya. There is a fair case to be made that that is not fun, that has nothing to do with WoW.

I don't subscribe to this viewpoint. In purely mechanical terms, perhaps it could be viewed as "failure," but I do not play D&D for a purely mechanical game. Those defenses aren't just arbitrary numbers--they represent a target's conscious effort to defend itself. If you arbitrarily increase the chance to hit, you have also decreased the chance for the target to defend. It increases predictability, and predictability breeds boredom.

He made one aspect of his game 1% more like WoW. The blasphemer. That's not even enough to call it convergent evolution, much less "inspired by WoW."

If it's good for his group, that's great. I hope they continue to enjoy it. I find his reasoning in opposition to my own experience, though, where the "failure" of the group can lead to some of the most memorable moments in our games.

 

[Grydan]

I must admit to finding his article confusing.

I thought I was following along just fine... then out of nowhere comes "These elements taken together led me to using a bell-curve determiner for D&D attack rolls".

Let me see if I have his position correct. Maybe I've misinterpreted somewhere.

He feels that the existing to-hit probability in D&D is too low for his group. This is partly due to the time players have to wait between turns. So he wants to adjust the probabilities so that his players hit more often.

Okay, that all seems perfectly reasonable.

Where is the leap to the bell curve coming from, though?

He says that a linear determiner is too swingy, but he's clearly fine with the existing probabilities of critical hits and misses, as he engineered his replacement system to keep the odds as close as he could to the existing ones. He also doesn't care for the random damage roll, but his change doesn't address this in any way.

It's the hit rate that he wants to change... but modifying the hit rate, predictably, is one of the simplest things one can do in a system with a linear determiner.

If you want your players to hit 75% of the time, rather than 65% of the time... lower all monster defences by 2. Everything else in the system works the same.

The only mechanical (rather than personal preference) thing his system actually gains over this, as far as I can tell, is the granularity he added to critical hits and misses, which wasn't his goal in the first place, and could have been added to the existing system in other ways.

 

[Goken100]

Wonder if anyone ever tried replacing the d20 with 2d10 for to-hit and skill check rolls in D&D.

I did in 3.5, and I recommend it. IMHO, the advantage of having a compromise between the extremes of d20 and 3d6 outweighs the minor annoyance of a 0.5 shift in average result.

I don't use the house rule for 4E, however. Not because it wouldn't work just as well, I just prefer to run 4E as written because I like it so much better than 3.5.

 

[thecasualoblivion]

The funny thing is, it isn't hit rate that really changes the dynamic of 4E's combat, its damage. There are few things that consistently boost attack rolls, and the 60% hit rate can be messed with, but only to a small extent. On the other hand, there are vast amounts of things you can do to pimp damage rolls, and you can get crazy with this. I have a four person group of level 21 characters that can consistently kill Elites in one round of focus fire, and a Sorcerer who can take off 3/4 of a Standard monster's HP total with an At-Will crit(the Sorcerer has severely boosted crits and a feat that lets them attack again as a free action when he crits with an At-Will).

 

[Goken100]

Speaking purely from a game design standpoint, non-dice pool systems (like d20, or any other system where you roll a single die) make it easier to predict the statistical impact of other game elements, like numerical bonuses and penalties. In d20, I can be assured that a +1 is always a 5% increase in chance of success, and -5 is always a 25% increase in the chance of failure, for example.

Bell curve systems (and, really, other dice pool systems) don't have the same level of ease of prediction. A +1 means different things based on how the dice fall. Plus, let's face it, the math is just harder when you start adding in multiple dice. Sure, you can do it, and game designers get paid for that kind of thing. But for casual designers (i.e. DMs wanting to homebrew) it slows down the process for most people. It's my personal opinion that a single-die system (d20 or otherwise) is easier to homebrew, and that's a good thing since it makes it easier for DMs/GMs to take ownership of their own game through house rules and homebrewed monsters, treasure, etc.

Rodney is a nice man who will hopefully continue to make wonderful toys for all of us. Its just that he's wrong right now, and here's why.

Point 1: I must quibble with 3d6 being lumped in with wilder dice games. A 3d6 system is not a dice pool system. Dice pool games are games where the pool of dice varies, thus creating an ever changing averages and variances. As a trained statistician, I too find such games abhorrent. But a system that uses a static number of dice, but it 1 die or 3, has a completely knowable statistical behavior.

Point 2: What Rodney might have been getting at is that the DM or game designer does not know the exact bonuses and targets of a given roll when awarding a shiny new +1 sword. A skilled character might already be hitting most of the time (be in the tail of the bell curve), so the +1 does not significantly increase the skilled player's success. But an unskilled player who hits only half the time (is in the middle of the bell curve) will be greatly affected by a +1. This disparity of probability affect is not seen in a linear distribution.

In conclusion, I do not think that Rodney's argument holds much water. Yes, probability changes depend on the relative position on the bell curve, but the random element is static. The game will hold up just fine. A +1 will always shift the difficulty of tasks that are reasonable to accomplish up by 1, no matter where you start. The value does not change based on "how the dice fall", as Rodney claims.

Cheers!

 

[Jeremy Ackerman-Yost]

I don't subscribe to this viewpoint.

No one said you had to. I just said that it's a defensible point. Fair discussions and arguments can be had on the point without needless hyperbole or accusations of badwrongMMOfun.

If it's good for his group, that's great. I hope they continue to enjoy it. I find his reasoning in opposition to my own experience, though, where the "failure" of the group can lead to some of the most memorable moments in our games.

That can certainly be true, depending on the table and the game. But there is tons of room for variance there while still well within the space of the hobby.

 

[Skallgrim]

I think that it is entertaining (though admittedly I didn't read the whole thread over there, just over here) how few people have actually had (or actually discussed having) experience with GURPS, which has been around for YEARS and has used 3d6 for combat and skill checks (since all combat is based on combat skills) for forever.

The long and short of it. A single +1 or -1 is going to radically shift the center of the bell curve. It has very little effect on the far reaches. Obviously, as it is a bell curve. However, what that means, in practice, is that a +1 (for a higher stat) or a +2 (for say, combat advantage) is a HUGE factor if your original chance of success was about 50%.

Given that PCs seem to be intended to have "success rolls" that are in the 50-65% range, this means that the PC who goes with an 18 rather than a 16 in a prime attribute is going to, on average, be MUCH better off in a 3d6 system than a d20 system. +3 Proficiency Weapons will be MUCH better in such a system. Any source of bonuses to hit will be MUCH more desirable in such a system, and will have a LOT more of an impact.

I suspect that if you adopted such a system, you would see a real decimation of race/class combos where the primary stat was not boosted by race, as well as a wholesale abandonment of +2 proficiency weapons. Weapon expertise would become MORE desirable than it is now (and now it is often considered practically mandatory).

The attractiveness of such a system in GURPS is because of three factors, none of which applies to D&D:

First, the system has lots of bonuses AND penalties, so it is possible to boost your chances to hit (say by using a telegraphed attack) and trade that off for a desirable outcome with a penalty (telegraphing that axe swing to the neck).

Second, the system depends on opposed rolls, so (except for criticals), it sometimes doesn't matter that you have an effective skill of 27 or less on 3d6. Your opponent has a dodge of 14 on 3d6, and so dodges 87% (or whatever) of your attacks anyway.

Third, the system (as it is point based) makes it MORE expensive to obtain higher skill levels. While D&D has this to a minor extent with the point buy system for attributes, after creation, it is no more expensive to increase an 11 to a 12 than it is to increase a 18 to a 19. In GURPS, the second increase costs substantially more than the first.

Go ahead and try it. You will get improved accuracy, but you'll see every problem with ruthless optimization made a lot worse, and you'll see the entire system become less tolerant of sub-optimal builds, I predict.

 

[Celebrim]

Go ahead and try it. You will get improved accuracy, but you'll see every problem with ruthless optimization made a lot worse, and you'll see the entire system become less tolerant of sub-optimal builds, I predict.

In the early to mid-90's I'd gotten sick of 1e AD&D for what I percieved to be a lack of 'realism', flexibility, balance and depth. I had basically all the common snears and slurs at 1e AD&D down. I adopted GURPS.

It took me only a couple years of actually playing (or trying to play it) to get sick of GURPs, and I eventually dropped it as a 'toy' system which read much better than it played and existed primarily to give rules tinkers something to tinker with. The list of problems I had with it was extensive, but the above criticism was one of the most salient (because it is an example of something that can't be fixed the way many of my other complaints were by 4e). In practice, the point buy system did not in fact lead to the broader, more versital, more 'realistic' characters that I hoped except by social convention (that is, everyone at the table prefered such characters and created them by choice). In practice, I found that it (and other point buy systems like WW's WoD games which I was also playing at the time) led to extreme hyper-specialization because that is exactly what the system rewarded.

Playing GURPS taught me alot about the effect of rules choices, design, alternate ways of looking at the world through the rules and it improved my ability to tinker with rules sets to achieve my actual desired goal. My current d20 rules are informed in several ways by my experience with GURPS. But I wouldn't actually recommend it as a game nor have I any desire to run it.

 

[RodneyThompson]

Point 1: I must quibble with 3d6 being lumped in with wilder dice games. A 3d6 system is not a dice pool system.

I do know there is a difference between bell curve and dice pool systems. I simply lumped them together because my point is that any system that uses multiple dice to determine outcome is inherently more complicated (for the purposes of determining statistics and probable outcomes) than a single-die system. I wasn't trying to argue that they cannot be used or are somehow bad for gaming, just that they are not as easy to understand the underlying probabilities in.

The game will hold up just fine.

I never said otherwise, nor meant to imply it.

A +1 will always shift the difficulty of tasks that are reasonable to accomplish up by 1, no matter where you start. The value does not change based on "how the dice fall", as Rodney claims

If I roll 3d6+1, the benefit of the +1 changes based on what I roll. If I roll a 9 and the +1 makes it a 10, that's a very small benefit from the +1, since I already had a 50% chance of getting a 10 anyways. If I roll a 16 instead and that makes it a 17, that's a huge difference, since the chances of getting a 17 are 215:1 against, and the odds of the 16 were 53:1 against. A d20 always produces a 5% increase in chance of success per +1, no matter what you roll.

Not that that's a bad or a gamebreaking thing. It's just more difficult for most DMs to figure out. That's all I'm saying.

 

[Jeremy Ackerman-Yost]

That's a little misleading. Admittedly, I'm close to reductio ad absurdum here, but if you are inflating specific points on the curve to make your point, I can just as easily say "If I needed a 17 and I roll a 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, or 18 that +1 is meaningless." After all, that +1 only has a visible effect when it makes or breaks the roll, which only happens when you're one short.

The shift of the curve as a whole is what's actually relevant to game experience over time. +1 will shift the mean by, well... 1. That's very predictable. You combine the switch in dice with knocking a couple points off the defenses of very high defense foes and the average player or GM probably won't notice there was any difference.

Exception granted for the numbers gurus around these parts.