Salvaging the d20 die

d20 die hugger

Note: I use italics to indicate quotes.

I’ve written at least a couple articles bashing the use of the d20 die in RPGs, for example: “Die, d20 die!”, “Die, d20 die! Part 2″, and “What do you want in a RPG? Part 7″ where among other things I said The d20 system actually has some really good mechanics that are worth salvaging, I just don’t think the use of the d20 die is one of them.

In response to the “Die, d20 die!” article, a user who goes by the screen name “LethalDose” commented   that a d20 roll is essentially a binomial (success/fail) distribution. The “natural 20″ critical hit result actually extends the sample space somewhat, but I think we can skip that part for the time being.  There’s really no point in the game where the numerical result of the a d20 roll directly has any bearing on the game. If the numerical result did matter, then the result of a 10 should be different, and twice as great, as the result of a 5. This is simply not the case in d20 systems.

I addressed these comments in the “Die, d20 die! Part 2″ by saying that a 5% chance of a critical hit was too small, which made a d12 a better choice, and that by Using a similar system with a d12 instead of a d20, you could add the excess (d12 + attack bonus – defense) to the damage roll; you can’t really do that in a d20 system such as Saga because d20 + attack roll – defense can be huge in some cases.

But something about that statement was nagging me, not that I didn’t think it was true, but perhaps it wasn’t the whole truth.  That got me to thinking about alternate uses of a d20 that might alleviate the issues I had with it.  And the result of that exercise is that I think I’ve found a way to salvage the d20 die.

In the “Die, d20 die!” article, I opinioned that the first thing that we as a hobby need to do is to hide all our d20’s in the back of our closets and only take them out when we reminisce fondly about great (for their time) old school games like Star Wars Saga Edition (best d20 system EVER)… well alright we can also take our d20’s out for miniatures games and massive delves at cons.

This comment holds a good deal of insight, not only on my part but on the part of Wizards of the Coast when they created their Star Wars Miniatures game. I assume but do not know for a fact that WotC’s D&D miniatures game uses the same basic mechanic: roll a d20 to determine success and weapons deal fixed damage.  As I was thinking about that I made the connection to a very different game, Fantasy Flight Games’ Edge of the Empire Star Wars RPG where weapons also do fixed damage but get a small added bonus, equal to the number of success symbols, that results from the dice pool roll.  And therein lays the salvation of the d20 die, a core mechanic for a system that I can best describe as “Sole 20.”  When someone makes a claim, I’m inclined to make a “show me the money” or “the proof is in the pudding” type statement.  I suppose I may be overly skeptical, but since I take that attitude myself, I’ve included a somewhat detailed summary of the “Sole 20” system below so that the interested reader can see that the system would actually make the d20 die work well if they were inclined to give it a test drive.

As the name suggests, the d20 die is the only or sole die used in “Sole 20.”   The basic mechanic is that you roll a d20 add a bonus from an attribute or skill plus a gear bonus plus maybe a favorable circumstance bonus minus a condition track penalty and then subtract off the target’s defense.  What’s left over is the damage that the target takes from the attack.  A natural 20 results in a “triumph” and a natural 1 results in “despair.”  Note that a “triumph” is not a critical hit; you don’t do double damage.  Instead triumph is a narrative mechanic where the PC gets a bit of narrative fiat to describe something awesome that happens similar to triumph in Edge of the Empire.  Despair in Sole 20 is also analogous to despair in Edge of the Empire or a critical failure which was a common house rule for d20 systems.  PCs can choose to store their triumph in the Karma by flipping a Karma chip from black to white; I’ll get to Karma a little bit later.

Sole 20 is a level-less and class-less system where the number of ranks in the relevant skill or attribute gets added to the d20 roll.  The set of skills is similar to the 50 in my 3D RPG; there are only 4 attributes: Acuity, Brawn, Charisma, and Dexterity and characters start with 4 points that they can assign to the 4 attributes with no more than 2 points in any attribute.  Each skill is associated with one of the attributes which is your minimum/default value for that skill but you can improve a skill to up to twice the value of the attribute by spending character points.  To improve it further, you have to increase the associated attribute (this increases the default value of all skills associated with that attribute similar to the relationship between attributes and skills in West End Games’ old d6 Star Wars RPG).  If you have one rank in a skill, it costs 2 character points to purchase your second rank; it costs 3 character points to purchase your third rank; the fourth rank costs 4 character points; the fifth ranks costs 5 character points and so on.  Increasing an attribute costs 10 time as much as it costs to increase a skill by the same amount.

Each attribute has a maximum value that depends on character race, for example: Elves would have maximum values of A5 B3 C5 D5; Dwarves would have A5 B5 C4 D4; Humans would have A4 B4 C4 D4 but can increase the any two of those maximum values to 5; Orcs would have A3 B6 C3 D5; Halflings would have A5 B3 C5 D4 but would get an extra point to Reflex defense for being a small target.  The preceding maximum values are tentative; I haven’t crunched the numbers but the “eyeball math” says that they are either as large as they can be for the stats to work right, or might one point too large.

There are four defenses in the game, each is associated with an attribute and defense skill: Mental Defense (Acuity & Discipline), Fortitude Defense (Brawn & Resilience), Social Defense (Charisma and Charm), and Reflex Defense (Dexterity & Dodge).  Your defenses all have a base value of 5 (or maybe as much as 10 depending on how the stats work out, I have a feeling that 5 may be a little too low), to that you add your ranks in the relevant defense skill (whose minimum/default value is the associated attribute).  You can add your armor’s damage reduction (DR) to your fortitude defense.  When someone makes a physical attack against you, you generally get to choose whether to use your Fortitude Defense (to resist it) or your Reflex Defense (to avoid it).

From what I’ve told you so far, it may seem like a no brainer to get the “best” armor that you can and use your Fortitude defense, but there are 2 draw backs to armor.  First, armor has 2 important stats, Damage Reduction and Dex Cap, which add up to 6 (for a traditional fantasy game) so if your armor had DR 5 your Dexterity would be limited to 1 which would in turn cap all your Dex Based skills (that were trained above your uncapped Dex) at a 2 (again eyeballing the stats, a total of 6 might be one point to high, this would be decreased by one point if the maximum allowed attributes were decreased by one point). Second, many weapons including all heavy blades have the “penetrate” quality which allows them to ignore a certain number of points of DR (armor’s contribution to your Fortitude Defense); for example: a broad sword (the lightest of the heavy blades) would have penetrate 1, a long sword would have penetrate 2 if wielded in 1 hand or penetrate 3 if wielded in 2 hands, and a two handed sword would have penetrate 4.  Since “penetrate” ignores DR it only applies against Fortitude Defense and then only when you’re wearing armor, i.e. it doesn’t affect Reflex defense but wearing armor does.

Weapons add “damage” to your attacks, the following numbers are tentative and actual values would depend on how the stats worked out: a knife would add one point; a short sword would add 2; a rapier and long sword would add 3; and a two handed sword would add 4.

In addition to the 4 defenses, characters have hit points and 3 condition tracks: Mental (applies to Acuity based checks), Physical (applies to Brawn and Dexterity based checks), and Social (applies to Charisma based checks).  Condition tracks have 5 positions: 0, -1, -2, -3, -4; these penalties are added (adding a negative number works like subtracting a positive number) to your dice rolls when you are down the condition track.  Characters move down the physical condition track when they take 5 or more hit points of damage from a single attack; they can choose to move 1 step up the Physical condition track by moving 1 step down the Mental Condition track.

Position tracking is a lot like in my 3D RPG (you can read more about it in “What do you want in a RPG? Part 6″), it’s tactical and designed to use miniatures on a grid of 1 inch squares; flanking grants favorable circumstances.  There are three narrative fiat mechanics: Karma, Themes, and character points.  The first two are similar to how I implemented them in my 3D RPG (you can read more about them in “What do you want in a RPG? Part 5″).

The Karma pool consists of 2 double sided black/white chips for each player at the table including the GM, at the beginning of the campaign half the chips start as white the other half starts black; PCs can spend white Karma to do things like trigger a triumph or void a despair; the GM can spend black Karma to do the same stuff.  You can also store triumphs in the Karma pool (by flipping a chip from black to white) instead of using them immediately.  Karma also functions as the morality system (see “What do you want in a RPG? Part 2″ for more details).

Your theme grants you favorable circumstances whenever it’s narratively applicable; you can have more than one theme but you can’t use more one at a time even if more than one is narratively applicable.  If you don’t already have favorable circumstances, you can spend a character point to gain favorable circumstances to one check; you can do this even after you’ve rolled the dice and seen the result. Favorable circumstances grant a flat +2 bonus.  The maximum bonus you can get from favorable circumstances is +2 even if there is more than one thing working in your favor.  There is no such thing as unfavorable circumstances; instead “the other guy” gets favorable circumstances which can increase his defense by 2 points.  Both you and the other guy can have favorable circumstances at the same time.

Character points are the meld of an idea of experience, money, and roll modifying mechanic.  Character Points and Karma are the only two “resources” in the game (see “What do you want in a RPG? Part 2″ for a definition of “resource”).  Once you’ve spent a character point, it’s gone for good but you can earn more character points.

So how does this solve my issues with the d20 die?

  • A relatively small number is added to the d20: the larger of a skill or attribute (which generally would be 10, for a maxed out character, or less), plus an equipment modifier (generally 4 or less), plus possibly +2 for favorable circumstances, which is possibly decreased by a condition track penalty (between 0 and -4), so the maximum size of the bonus is about 16 compared to easily being well over 20 in the d20 system.
  • I dislike using separate rolls to determine success and effect as it slows game play (and for other reasons that I will address in the next few bullets), and this “Sole 20″ system has a 1  roll resolution mechanic.
  • The entire distribution of the d20 matters, it’s not transformed into a binomial-ish distribution by the roll interpretation mechanic (I agree with LethalDose about this); this is because the excess of the roll plus attack bonus minus defense is the damage.
  • Using the excess of the roll as damage is not a problem in this case because the excess is much smaller than in d20 systems (such as D&D 3.5, 4e, and RCR and Saga edition Star Wars) and because it is not added to separate damage rolls.  The d20 die “does not play well with others.”
  • The system doesn’t need or have critical hits because a natural 20 already means you’ve rolled the maximum possible damage.
  • The system does have “triumph” and “despair” on a natural 20 and 1, which are narrative mechanics that are similar to their implementation in FFG’s Edge of the Empire Star Wars RPG; an “advantage” could be generated for exceeding the difficulty by 5 and/or 10 points.
  • The 5% rate for triumphs is a little too low for my liking (optimal rate is between 1/12 and 1/14), and could be adjusted to occur on a 19 or 20 (but a 1/10 rate is probably a little too frequent).  However, the Karma mechanic allows PCs to choose when triumphs occurs, which helps alleviate the too low frequency.
  • The 5% rate for despair (on a natural 1) is about the maximum it could be for good statistics, but the Karma pool also lets you void/delay them.

I hope I’ve given you enough evidence (give it a test drive type evidence) that it is possible for a d20 die to work well statistically.  But as I’ve said in my “Die, d20 die!” and “Die, d20 die! Part 2″ articles, how the d20 die is used in currently published d20 systems just does not work well from a statistics view point.

I contend that most RPG designers should pay a lot more attention to statistics than they do today, but to be fair: not many game designer have had advanced mathematical training and for a lot of people it takes seeing something that works really well to recognize that what they’re familiar with doesn’t.  I know that I was completely unaware that skill points in RCR Star Wars and D&D 3.5 were a nightmarish Frankenstein Monster game mechanic until I saw the Star Wars Saga Edition skill system.  My hope is that once my 3D RPG hits the gaming tables en masse that:

  • game designers will stand up and take notice that its stats just work really well,
  • a similar light will go on, and
  • then they will start applying a much more quantitative approach to the design of their own games.

Seriously, do us all a favor and take the time to make sure the math/stats work out right.

Peace out.

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