I Like My 20-Sider
Last week I talked about how I was designing a new system rather than using the well-known d20 System that I helped create. The d20 System, of course, gains its name from the fact that its most common die roll is the d20. It lies at its core mechanic.
And I must admit, while I don’t want to use the d20 System for my current project, I still really, really like 20-siders. There’s something uniquely satisfying about its shape and how it feels in your hand. There’s something iconic about the thrill of rolling a 20 and the crushing defeat of that oh-so-terrible 1.
The Flaws of the d20
There’s some problems with my favorite die though. Using the d20 introduces a great deal randomness into a game. It’s difficult to use a d20 as a task resolution die and still have character aspects play as a big part in success or failure without all of a sudden finding yourself using pretty big numbers. A smaller die would offer a narrower range, and a set of dice (say, 3d6 or something) offers a nice, reliable bell curve.
For example, consider a smaller die, let’s say the d10. Once I’m adding at least +6 to a d10 roll, what I’m adding is more significant than the die roll (averaging 5.5). So anything from, say, +3 to +7 makes your bonus–presumably coming from your training, natural ability or both–very significant. It means that capable people aren’t going to fail as often as those with less training. But with a d20 (averaging 10.5), those same numbers would have to be much larger.
Worse, there are wild and wide swings of randomness with a d20. Even though the “average” is 11–we’ll round to the nearest– you have just as much chance to roll a 20 as an 11. (And I put “average” in quotes because it’s more accurately the “median.”) Let’s say someone who doesn’t know what he’s doing with a bow adds a +1 because he’s got decent hand-eye coordination. Let’s say you’ve got an archer with some skill who adds +8. Now let’s say that the target number to hit a bullseye is 20. The archer hits that any time he rolls a 12 or higher. That’s 45% of the time. He’s awesome. But the guy who’s never picked up a bow before still hits the bullseye (not the target, but the bullseye) 10% of the time, just because of the way the die works. Now imagine that you used 2d10 instead. 2d10 gives us a more normal distribution. In other words, you end up with a much better chance of getting a 10 than a 20. Using the same bonuses, the archer still hits the bullseye 45% of the time, but the unskilled guy only 3% of the time. That makes more sense.
But man, I like how that d20 rolls. And so do a lot of gamers. Plus, using one die means I’m not adding two numbers together all the time. (Or, in the case of a dice pool, searching through a bunch of dice looking for those that give a certain result.)
Easier on the GM
There’s another big advantage to one die. If you’re using a system where the GM has to assign a target number for a task, it’s a lot easier to do that on the fly with a d20 than, say 3d6 or 2d10. Why? Because with a d20, the difference between, say, 17 and 18 is the same as the difference between 8 and 9. They’re basically just 5% increments. That means that if I figure a character should have about a 75% chance of success, the target number should be 6, because I’ll roll a 6 or higher 75% of the time. With a bell curve, that’s a lot harder to figure for the GM, particularly on the fly. And one of my goals is to design a game that is very easy to run.
Of course, that assumes just a flat die roll, without modifiers.
I am currently working on the premise of using the d20 as a task resolution die, but without a lot of situational or character skill or ability modifiers, and a different set of assumptions about what it means to be good at something. Basically, things like skill and favorable circumstance don’t add modifiers to your roll, they change the target number you’re looking for. While this is mathematically similar, the target number is reduced in large, meaningful steps that are quite different than a +1 to the roll, most importantly because you can reduce the target number down enough steps for assured success if you’ve got a lot going for you (or the task wasn’t that tough to begin with).
What that means is that you’re not often adding much to the roll. Most of the time, nothing at all. It makes task resolution–and in particular combat–move much, much more quickly if you’re not waiting for people to add together numbers (or to ensure they have all their various miscellaneous modifiers accounted for). Setting target numbers never has to involve ridiculously high values, even for really tough opponents and/or PCs. If you’re never adding more than a bit to the roll, the d20′s numerical steps become 5% steps, more or less, which is intuitive and easy to work with.
Now, of course, if that’s true, game-design-wise I’m just a few changes away from using a BRP (i.e., Call of Cthulhu) style percentile system–which is a game system I’ve always loved too–but now we’re back to that whole d20-as-visceral-object-I-like-to-roll issue.
Player Authority
As I wrote earlier, I’m toying around with ways to give players more authority over their own characters’ actions by allowing them to focus their effort at certain times. This can be expressed as a way to further lowering of the task’s difficulty a few steps (rather than say, a bonus to the roll). This particular setup also allows me to play around with a lot of factors. I could, for example, attach special properties to either natural die rolls (not unlike a crit on a nat 20 but expanded, or developed differently) or, alternatively, I can attach those to the lowering of the target number, which puts more authority in the player’s hands and less in the dice. Or maybe even some combination of the two.
There’s still a lot of development to do, and ideas are actually changing and evolving on the project very quickly at this point, but that’s how it looks at this moment. More alpha testing may develop this further.
One Last Note
Before you ask, I’m familiar dice pool mechanics, and enjoy games that use them. I haven’t mentioned them in the above analysis, but I considered different dice pool mechanics in my design. Most end up producing a bell curve (or something similar) of results, and I know that a lot of people like bell curves. However, the conclusion that I came to is that I’m not sure a more normalized set of results is right for this project. First of all, like I said, it’s harder on the GM to assign difficulty. Second, I like the flat progression and the swings of fate it provides.
But like I said, I know that a lot of people like bell curves. Playtesting may show that something more like 3d6 is better than 1d20. If I want a more normalized distribution, though, I lean toward 2d10, actually. And here’s the thing–the game system that I’m working on is simple enough that it would be easy to include rules for using different die mechanics right in the rulebook, say in an appendix. There would be implications, of course, and I could cover that. 2d10, for example, would make easy tasks easier and hard tasks harder, but not so dramatically that it wouldn’t be workable.
Or, if I wanted to go really crazy, I’d use a mechanic that would allow me to keep my beloved 20-sider and yet produce a bell curve. To do this, you just roll three twenty siders and ignore the high and low rolls of the three. Very weird in game play, but it would end up with normalized results.
Dice are funny little creatures. They really can do a lot, though.
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I really like D20s as well. They are the most fun dice to roll, either singly or in pairs, and the shape and feel of a 20 sider evokes something visceral, kind of like an old song you loved when you were a teenager, or remembering the smell of your mom’s cookies baking on christmas eve.
Have you considered using something like the old Marvel Superheroes task resolution system? One of the best homebrewed rules systems I ever had the pleasure to play in was based on the ‘column shift’ concept and a master task resolution table. That was a ‘linear roll’ system where the modifiers were small, but important, since they changed the whole shape of the curve. (Each column got to have its own separate ‘bell curve’, with the higher columns having a much higher change of critical or supercritical success). A +1 column shift magic sword was nothing to sneeze at in that game. I think the biggest problem we ran into was that it was easy to allow too many of those +1s, so you had to be careful to set limits (i.e. use just largest or the two largest + modifiers together)
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Hmm, how about a dice pool mechanic that uses D20s? That way you can use more than one d20 at a time (which is supremely satisfying) and still have a dice pool mechanic.
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Just a suggestion what about the Roll and Keep style of Legend of the Five Rings? It does balance out many of the misgivings the single die roll has without adding the problems of a dice pool… And it gives a lot more freedom to players and GM on their actions (given how the roller choses which dice he keeps).
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I personally love the 2D10 mechanic. It’s nice to “curve out” the flat D20 and the same dice can be switched to D% mode instantly for tables and such. All the old D20 games can be cheerfully vandalized by substituting 2D10 with some minor tweaks, producing a feeling of instant realism in an otherwise chaotic multiverse.
I’ve always enjoyed dice, however – in all their manifestations – and the DCC RPG with its “Dice Chain” of D3, D4, D5, D6, D7, D8, D10, D12, D14, D16, D20, D24, and D30 is perfect for dice fetishists who relish a bit of “old school” nostalgia in a new framework.
That being said (and all fetishes aside) there’s something elegant about being able to put a pair of D10 dice in your pocket and gaming away without piles of assorted polyhedrals all over the place. The D4 in particular is a nasty tank trap on the floor, just lying in wait for those barefoot nocturnal wanderings.
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I like the d20, too. Looks cool, feels cool. But using that as a rationale seems dubious.
Roleplaying is all about player interactions. One place this is taken over is during the dicing and calculation phase of the game. This phase is critical, of course, but it takes the player out of right brain space and lands them in left brain space. The roleplaying stops while the math brain works out the main chance. One way to ameliorate that experience is to allow the player an increased degree of participation in that rolling phase.
In d20 or single dice task resolution…
Typically, the GM sets a target number or difficulty and the player responds with their best response (weapon, spell or skill). The target number is set, the response modifiers are set and here comes old d20 to give you the flat, wide variance. The target was 12 (simple task), the modifiers were +5 (plenty of skill) and the roll is a random 5. Doink! This has never made complete sense to me. Don’t I have a better chance than that?
In pooled, roll/keep, variable difficulty mechanics you have a ratio of skill to stat in play, a pool of dice for bell curving and the ability to increase the difficulty for roleplaying juice.
How much better when the GM sets the target number for NORMAL success (ie you accomplish the simple task of jumping the creek with no extra flourishes) and the player then looks at his skill mods and his stat scores and determines that rolling 3 dice (jump skill of 3) and keeping 2 (dex stat of 2) is going to make the check handily. If he succeeds he has a normal success (he simply jumps the creek) and if he fails (he simply slips or gets wet)
However, the wants to bypass normal success and RAISE the difficulty (conspiring with the GM). He can go further and ask for a raise in difficulty but what he wants something SPECIAL in return (to jump an further AND tackle the escaping rider he is pursuing). The GM raises the difficulty and the player roll dice equal to his skill and keeping the number equal to the relevant stat (high numbers are typically kept). Its a tighter chance now, but the player has an ACTIVE rather than PASSIVE role in the “roll playing” aspect of the game. If he succeeds he has effectively created his own critical success (Tackle on horseback!) and if he fails he fumbles (Trampled underfoot).
Pools, Roll/Keep and Raises creates a solid, consistent and flexible core mechanic that confounds that age old problem of players downshifting out of earnest role-playing as soon as the roll-playing starts. It seamlessly creates a better curve, a simpler mechanic that is easy to follow and logically consistent, a method for players to selflessly increase difficult in return for player driven enhancements and a built in crit/fumble system. Elegance.
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@Ian. This is the system I am referring to.
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Just use icosahedral D10′s, Monte!
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While I love playing d6 based games (GURPS, Gumshoe, and so on), I miss those other dice. d20s, d100, the much neglected but very cool looking d12, and the rest, they call to me and want to come out and play.
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I am partial to dice pools myself. I like the idea of rolling more than one d20. With pools eliminating the fiddiness is important in my opinion, so I do like the idea of just taking the highest roll. I also like the d10+modifier because it puts more weight on skill and talent.
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The more I hear about this project, the more interested I am. As yourself, and so many posters, there’s a visceral and nostalgic attachment that we have to the 20-sided die. And I agree that the flat progression adds drama to task resolution, which is what a good game always involves. The best stories are always about that tremendous quirk of fate, rather than the statistically-likely success or failure.
It _sounds_ like the resolution system you’re devising doesn’t necessarily reduce the amount of math involved, but instead moves the adding and subtracting over to the GM. I have no problem with this; I’m talented with simple mathematics and years of gaming have honed that skill. And I’ve definitely lost players due to the insane amount of math involved with 4-5 people swinging swords and casting spells with mid-level characters in the d20 system.
Anyway, more and more interesting! (And I would give my eye teeth to be in on the beta-testing.) Keep it up.
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I’ve never really understood the critique of the d20 as “too random” for resolving binary challenges (hit-miss, success-failure). Any binary challenge is just a % chance of success–so if a system feels too random to you, it’s not a matter of which dice you are rolling but how big a bonus you are assigning for PC skill. If you have a “bell curve” to-hit roll that succeeds 70% of the time, that’s exactly as random as a d20 roll that succeeds 70% of the time.
Monte’s decision to make PC skills add big chucks to the chance for success is right up my alley. You keep the easy math of a single d20, but the difference between a skilled PC and an unskilled one is much less likely to come down to a roll of the die.
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I think people mean generally how d20 has been done it tends to be more on the random side. If the bonus is big enough or you do roll under generally high numbers or roll over generally low numbers it tends to put more back in the realm of skill and talent of the character (2e NWPs are a great example of this where if you have a decent stat for the NwP, then your chances of success are generally pretty good). But in the d20 system you have a floating 1-20 bonus on top of your skill level. Unti your bonuses get pretty high, the luck of the die has a big impact.
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Have you considered taking an idea from modern wargames and using a “DBA” style roll? DBA (“De Bellis Antiquitatis”) was the first set to use a system of opposed d6 rolls where beating your opponent gives a small success, but doubling your opponent’s score gives a major success. This adds an extra dimension to the die roll mechanic, in that a +1 modifier for you is very different from a -1 modifier to your opponent; both increase your chance of a minor success, but the -1 also boosts your chance for the big win.
For a roleplaying game, I would imagine using d10s would work well. Net modifiers should be in the range -3 to +8 normally, to leave a (1%) chance for the underdog in a +8 vs. +8 contest to get the double (i.e. player 1 rolls a ’1′, for a total of 9, player 2 rolls a ’10′, for a total of 18 – double the 9).
This mechansim keeps the 1 die (per side) and provides a nice range of bell-curved result spaces, but it does require moving away from “DCs” to always give an opposed roll with a modifier (i.e. you give modifiers as task difficulties, rather than DCs).
Just a thought – other game types are worth watching for neat mechanics, I think.
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Many systems go on the ‘wounds’ system. The more dice, the better your weapon and training. I’ve played two where 5s and 6s on a d6 are successes and one where 4-6 are positive results. With a d10 you could do the same sort of thing or use percentages (2d10= d100). These are proven systems, though difficult ones to be masters in. D12 or 8 is what I’m concidering. But why waste the other dice in the set? Perhaps that d20 could be rolled for tables or side-effects.
As for the rpgs themselves, I still think the games that have role-play (character interaction) over combat are more interesting than those that the rules are stat driven for combat. Combat is very important, but table-top games are for interaction. I like your article, Monte. You know your dice and what gamings about. I’m sure you’ll have something unique and fun for us! -
A tough situation indeed, Mr. Cook. I’ve tried as many systems as I can get my hands on, from d20 (and similar basic mechanics, like Dragon Age’s 3d6), and the d20 still feels incredible. I love your mention of the 2d10 creating the averaging curve, that only affects the weak and not the strong; 3d6 creates this same effect (lower maximum, obviously), but I always come back to the d20.
I remember Alternity using the d20 rather uniquely, having it roll low, specifically beneath a stat instead of adding directly to the d20, and this was a pretty good feeling as well.
Whatever you go with, however, I entirely agree with you that the current random dynamic takes too much control from the player, and I eagerly await your alternative. -
I’ve personally found that my fondness for the probability curve of 2d10 outweighs the visceral allure offered by any other dice combination.
2d10 offers a result range broad enough to allow for meaningful modifiers, but a small enough result set for a GM to still grasp the probabilities involved. It’s stable enough for a character’s underlying aptitude to carry more weight than chance. but wild enough to know you still can’t take success/failure for granted.
I’m also much more comfortable with saying, “All right: it’s nearly impossible, but I’ll still give you a 1% chance of success,” than I am with saying, “All right: it’s nearly impossible, but I’ll still give you a 5% chance of success.”
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Come on Monte, join the crunchy side… Roll-Under Percentile! Make 00 Buckshot mean something awesome once again!
Anyways…. As much as I enjoy the ol’ d20, I feel that the d20 System doesn’t handle the variance the 1-20 linear range provides very well. The equal probability to get a 1 or 20 can be absolutely aggravating when playing low level characters. Sure in theory the statistics dictate equal probability… as the number of rolls approaches infinity. Until then, the die can troll you relentlessly for sessions on end. And the “roll with bonus/penalty to meet or beat a DC number” mechanic can be folly to DC or bonus/penalties not being in proportion. That mechanic can easily make you ready to abandon low level characters after a sour session of bad rolls. And at higher levels, the accounting it takes to do a roll can’t take forever to work out.
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I too like the d20 over the d10. I suggest you do what I do to resolve this. Use a 20 sider numbered 0-9 twice, just like back in the old days. Then you can have all your d10 die mechanics with the satisfactory feel and look of the d20.
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I don’t think I’m following this part: “Basically, things like skill and favorable circumstance don’t add modifiers to your roll, they change the target number you’re looking for. While this is mathematically similar, the target number is reduced in large, meaningful steps that are quite different than a +1 to the roll, most importantly because you can reduce the target number down enough steps for assured success if you’ve got a lot going for you (or the task wasn’t that tough to begin with).” If, for instance, unmodified success requires 10+ on d20, adding a +4 bonus to the roll is not just mathematically similar but mathematically *identical* to instead directly reducing the target number to 6. I understand that you’re aiming to control the modifiers to prevent number-escalation, but I don’t see where shifting DCs instead of modifiers fits into that strategy. Could you clarify?
On another note: the thing I like best about the d20 system’s use of the d20 die is the mechanic to take 10 and take 20. This covers cases like allowing skilled characters to auto-succeed at routine tasks, and adds some game-mechanical texture (like allowing high-level rogues to take 10 on skill checks even when they normally couldn’t) in a way that doesn’t just inflate the numbers. Very cool.
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The reduction in difficulty is done in large, more easily-managed steps rather than in miscellaneous small bonuses. So it’s not a system where you gather up a bunch of +1 bonuses from a bunch of sources. Reduction in difficulty in these steps also can have other game effects tied to it as well, such as “reduce the difficulty in three or more steps and gain this special effect.” It’s another tool in the design toolbox.
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“With a bell curve, that’s a lot harder to figure for the GM, particularly on the fly” — referring to target numbers, you are of course assuming that the task resolution for the dice pool mechanic uses an additive TN, rather than a success per die TN, such as the Burning Wheel. That games uses d6s, with a TN that’s almost always 4. The DM assigns the difficulty (or Obstacle) based on the number of successes required, that method is really easy on the DM. Sorry to point out the obvious, but it does depend on the kind of dice pool you use. In any case, the project sounds interesting, I for one am somewhat interested in any game that could make using the d20 seem fun again. These days, I’m totally against anything that isn’t d6 or d10 based, whether a TN per die dice pool, or Vincent Baker’s Apocalypse World and it’s various hacks (2d6 versus a TN of 7, with better results achieved on a 10, or potentially a 12+). Good luck! Incidentally, never got the chance to play 3rd edition, but owned the core books and read/purchased some of your material. I always thought you had the most interesting perspective on tweaks to the system!
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Come on, live dangerously. Go for the D30.
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I’d love to use my D30 more often.
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If you want a bell curve and d20 skills, how about just setting out all the difficulty numbers in a big line? Then you start in the middle and step up or down based on how your skill outmatches or is stretched by the environment.
So whenever you roll the dice, you look at the same piece of paper that does everything. All other “stats” and whatever else are just descriptions of the world to help us keep track of which way the advantage goes.
The trick is that the steps are not all even, so that you move in small increments in the middle and larger ones at the two edges, until you get to autosuccess and autofail.
This doesn’t represent degree of success in any way, but if what you’re interested in is “larger differences in skill are proportionally more significant”, you can cover it this way.
eg the scale could be
autosucceed, 1, 5, 8,10,11,13,16, 20, autofail
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To anyone thinking, hang on, that scale is borked, yes, I just noticed; it doesn’t specify “”beat this number” or “equal this number”, and either one would spoil it’s symmetry. As a fix, make it so that exactly rolling the number you need is some kind of marginal victory/apocalypse world style ugly choice etc, so that the 1 and 20 options still mean you’re rolling for something.
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Fading Suns had something like this. Since the designers were former White Wolf folks, they modded what they knew. Roll a D20. You had a target number to roll under. The closest you came to the target number the better. If you rolled the target number exactly, you had a critical success.
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So, every exchange in cobmat involves you rolling your attack and me rolling my defense, and then vice versa? I think that will slow things down more than you think.What about static threats, like surviving exposure or leaping a chasm? Does the chasm roll to stop you from clearing it?I have a variant that I want to use at some point, in which the DM never rolls any dice. Effectively, all the NPCs take 10 on every roll. The only changes under D&D 3e is that players roll their defense instead of just adding 10 and they have to roll spell attacks instead of declaring a save DC. Simultaneously frees up the DM and keeps all the players engaged through the whole round.
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No, you don’t roll twice each time in combat. You roll once. But it’s always the player making the roll.
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I love my d20. I have a few but my orange one is significantly better than all of the others combined. It is solid, heavy and rolls well.
That said, the big benefit of 3d6 is what I called the CVS factor. If you’ve got a rules light system, new players don’t need to go to a specialty game store to get dice. They can just head over to the local drug store and boom, there is a pack of 5 dice ready to go.
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Well I’ve always liked the roll and keep system, but I’ve also liked d% systems as well. *shrug* I “grew up” gaming systems like Rifts and FASA. I’ve only recently gotten into D20 with a group/dm that’s been able to keep my interest in the game.
Over the last year or so, I’ve stumbled across a number of systems that I thought had interesting aspects of affecting chance and results. Bayrn.org uses a D6 pool system where the size of the dice pool is largely affected by the players description of the characters actions. The roll/keep+raises also encourages a degree od activity as previously mentioned. Speaking of…. Wick recently released a mechanic where the degree of success a player acheives gives them a degree of control over the result description. I’ve also been interested in seeing the dieshift mechanic in use in an RPG. I’ve played a few of Jon Tuffley’s wargames which use die shifts and they seemed to work fine in a tactical RPG. I’ve heard folks argue against die shifts because you “change the probability”. But, in all reality, isn’t that what skills and modifiers are for? Changing the probability of success or failure? To some degree, this article touches on something that has bothered me for a while, where die results count more than the character does. It’s rolled around in my head a bit that the more skilled in something a person is, the less effect dice should have on success. In that same vein, roll for failure instead of success? Then the dice used would be based on how likely you are to fail instead of suceeding.
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I’m a recent convert to Stolze’s One Roll Engine. You have a dice pool of D10s and look for matching sets of numbers, like Poker. It’s simple and elegant, but there aren’t target numbers generally.
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I have a pink d20 that players in my Mutants & Masterminds game have learned to fear and dread. It rolls really high a lot.
My own experience is that pool systems overall tend to be less ‘swingy’ than single-die systems. The problem with this is that it makes both the high and low ends less likely, and takes some of the drama out of it.
Always remember, though, the Dice Gods hate everyone. This includes you.
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Hollis, you and I should sit down at a table together one night and I will show you just how much a d20 can hate someone. Not just one d20, *every* d20. I don’t know what I did to them in a former life, but it must have been really bad. I have considered just going to my d12′s, they would provide me with the same results without taunting me with the promise of a “Nat 20″ once every 6 months. Please do not think I am exaggerating, my fellow party members were so excited for me one night, they wrote down on our game board – “On 2/22, Monica scored 3 critical hits in one game session”. That was February 22, 2010. Yeah, now we just keep it up to remind ourselves of the good old days when the d20s at our table pulled a practical joke on me.
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