Compleat Character Creation Catalog: OD&D

On the Wandering DMs a few weeks ago, we had a neat conversation about the history of generating ability scores for D&D across the various editions. This brought to mind a post I've wanted to make for a long time: in early D&D, what are the odds of qualifying for desired character classes, given the various methods presented for generating abilities? 

A few folks have worked on this problem previously. Probabilities for the 2E AD&D game rules were given by Ed Friedlander in Dragon Magazine #153, January 1990 (thanks to Dominic Brown for tracking down the reference!). One of our viewers pointed out that the Athenopolis.net blog had done basically the same thing for 1E a few years back. Actually, I think that was extremely helpful, because it gave me a nice opportunity to double-check my results -- we mostly agree on the major stuff for 1E. However, there are a few fine-print rules I think they overlooked there, and I've added more statistics, commentary, nearby editions, and so forth.

To avoid an overly long post, I've broken this up into separate articles: you'll see OD&D, AD&D 1E, and Unearthed Arcana (UA) 1E variant rules. Some opening ground rules: For simplicity, as others have done, we're basically only looking at the raw ability scores generated for single-classed human characters. We're not considering the after-the-fact racial adjustments from AD&D, the chances to qualify for multi-class combinations, dual classes, etc. All of the statistics you'll see were generated by Monte Carlo-type simulations from a C++ program, which you can see on my Github: ADnDClassAccess repository. Having noted that, let's begin:

Ability Generation Method

It probably bears without saying, Original D&D has only one way of generating ability scores, the classic 3d6-in-order procedure for all six ability scores. But some things that may be surprising about this: The rulebook says it is the referee that should be making these rolls (proto-pregens, perhaps?). There is a vague point-swapping method that allows you to trade a few points into your prime requisite, maybe (more on that in a bit). And despite many people's incorrect memory, this method was not supported in any way by the 1E AD&D books (although it was carried forward into the D&D Basic line).

The statistics for the standard 3d6 roll are fairly well known. (For example, it's the default sample roll for Torben Mogensen's excellent Troll dice roller and probability calculator). It has a symmetrical bell-shaped curve, with an average (mean, median, and mode) of 10.5, and a standard deviation close to 3 (2.958).

Okay, so about that point-swapping rule: Descriptions of the abilities say things like, "Strength is the prime requisite for fighters. Clerics can use strength on a 3 for 1 basis in their prime requisite area (wisdom)...", which would get me thinking this purely an additive bonus thing. But then the next page says, "Units so indicated above may be used to increase prime requisite total insofar as this does not bring that category below average, i.e., below a score of 9", so that makes it seem more like a points-swapping mechanism. But then the 5th printing of OD&D (at the same time as the Greyhawk supplement presented more advanced ability modifiers) added the clause "... for the purposes of gaining experience only", so maybe it's not meant to be a factor for class qualifications or combat bonuses? 

In short: the status of point-swapping rule is very unclear. As noted above, Holmes with his Basic D&D line took this as a key rule, and made the points-swapping explicitly permitted (and it was continued forward by Moldvay, Mentzer, etc.). But Gygax gave no hint of its presence in Advanced D&D. Recall that at best it's only for the very limited purpose of swapping a few points into one's prime requisite -- which as we'll see, is usually not really a requisite at all...

Classes and Requirements

Here's another thing that might be a tad surprising to longtime players of AD&D, say: in the Original D&D LBBs, there aren't any ability score minima to qualify for any of the classes. You can definitely enter any of the Fighter, Magic-User, Cleric, or Thief (from Sup-I) classes, regardless of what your ability scores are. In fact, the one example of a character being created highlights the player not picking the class according to their best ability. Moreover, the table of bonuses and penalties from ability scores includes the line, "Prime requisite 6 or less: Minus 20% from earned experience", so while that stings, it's clearly not prohibited -- and demonstrates my point that "requisite" isn't quite the right word for it (yet). 

Then, in the various OD&D supplements (I through IV) and The Strategic Review zine articles (issue #1 through #7), we sequentially start adding all of the various sub-classes that we ultimately see collected in AD&D. This is where ability-score minimum gateways come into existence, starting with Sup-I stating that lawful fighters with a Charisma of 17 or higher can gain "paladin status". Note one detail: even though Strength is their "prime requisite", there's still no actual minimum requirement for it -- under those rules you can roll all-3's but a 17 Charisma and still be a paladin. Some later sub-classes, like the Ranger (TSR #2, by Joe Fischer) and Illusionist (TSR #4, by Peter Aronson), continue to give no minima in their prime requisite, while other ones do add such a requirement.

This further highlights that swapping points into the prime requisite wouldn't make any difference in most cases for qualification purposes, while there's no allowance for swapping into the other abilities that do have requirements (like the Paladin's need for a 17 Charisma). So in conclusion, due to the great unclarity of the status of the rule, and the overall low impact on the question of qualifying for classes, we won't be considering that rule further here: it's just straight 3d6-in-order for us.

When all is said and done, here are the various classes indicated in OD&D and its supplements, with their ability score requirements, as best as I can read those rules (presented in order of publication of the classes):

Qualification Chances

At last, we can run our simulator with the straight-3d6 method against the OD&D class requirements, and derive the following chances for any new character to qualify for a desired class: 

As noted above, we see the 100% values for the four primary classes, because there's no ability-score restriction on entering those classes in the LBBs. On the other hand, the sub-classes are all generally very hard to qualify for, usually in the range of 6% or less. There's less than a 2% chance to get the divine Charisma of 17+ that qualifies you for Paladin status (justifying many of our memories about the intense celebration that would erupt if anyone ever got to play a Paladin). And the Monk is even more insanely difficult, at just a third-of-a-percent chance (thanks, Dave). Although surprisingly for AD&D fans, the OD&D Bard has fairly gentle entry requirements, and so is actually the easiest subclass to enter, with 14% of any PCs qualifying (and you can do so immediately: no need to level up through other classes first). All of this will change when AD&D overhauls the rules, of course. 

I suppose, in review, given all the complicated methods that came later to give players more fine-tuned control over the starting abilities of their characters, there's some charm in the germ of the idea that's already in Original D&D -- allowing for limited points-swapping following the straight-3d6 rolls. Say we streamlined it and made it always at a 2:1 ratio (drop 2 points in one ability to gain 1 point in another), as we see in Moldvay, not to reduce any ability below 9. We could then pick from a few options for swapping allowances: (1) only from Str, Int, Wis, Dex into one's prime requisite, (2) from any ability into one's prime requisite, or (3) from anywhere to anywhere, at the player's discretion. A rule like this has the elegance that brand-new players can simply take their 3d6-in-order without further consideration, while expert players can dig into the customization possibilities.

Anything surprising to you in those results? Are there any OD&D rules that you interpret differently than I did? Would you consider using some form of the streamlined 3d6-with-point-swap rule outlined above? More fun with AD&D next time.