The common explanation by the wider OSR for as long as I've been listening has been, to replace the Chainmail combat system and to provide a universal mechanism for hit resolution - separating the Chainmail game from the original edition in all but a reference. For a long time, I accepted this explanation: it made sense, all of the clones I had seen used the ACS with no mention of mass combat or of Weapon vs Armor, and having not invested in the original booklets, even the inexpensive PDF option - I was playing Basic: why should I worry? Why should I concern myself with it? - I had no reason to disbelieve the gray-hairs who maintained the original edition was a free-wheeling one: an incomplete game which required continuous ruling and referee improvisation to form into a collective experience - later to be completed in the 1st edition, with all (or at least most) of the cracks and crevices puttied.
Since then, I've been disabused of that error.
While there is no reason not to use the ACS in your 0e game as the primary it resolution mechanism - I'm not here to have that debate - it's also not the reason the ACS was included. In Chainmail - included in the same "recommended equipment" section as "dice" and "players" - two tiers of play surface: the normal scale, comprising orcs, men, and the like; and the heroic scale, the fantastic scale - comprised of wizards and dragons and heroes! To fight between these creatures leveraged the Fantasy Combat table: which functioned much like the Man to Man, providing a target number on 2d6 for one side to come out victorious: with the probabilities influenced according to the literature and mythology informing them: Wizards and Balrogs, an homage to the bridge at Khazad-Dum; Heroes and Trolls; to Anderson's Holger Carlsen. Knowing this - the matrix between each disparate type is necessarily as large in both rows and columns as the number of supported monsters: in a game with potentially endless enemies and mythologies from which to draw them, such a matrix becomes untenable! First - competing mythologies may have no overlap: how should the Pondo impundulu bird fare against a Mesoamerican chaneque?
And second - citing Gary's own rationale from the proto-D&D (or Pre&D, as I like to call it), to create a matrix in that manner would rapidly exceed the available margins. What worked for a tightly bound fantasy wargame - Chainmail Fantasy Supplement - would not be feasible for the new, unbound idea that would become Dungeons & Dragons.
So - suffice to say - the original combat system being alternated out was the Fantasy Combat system, not the Man to Man or troop combat systems previously defined.An Alternative Alternative
So - what am I up to?
One of the characteristic elements of Chainmail and of most wargames is their dependence on the d6: specifically, both Man to Man and Fantasy Combat use 2d6 against a target number for hit resolution. By introducing a d20 based ACS, a totally separate mental mechanic is introduced - so, instead, why not stick with 2d6: retaining the curve and dice feel, but producing the same outcome - a universal approach to replace the confines of the Fantasy matrix?
While gaming at home - in off hours with my older offspring (when their mother isn't looking) - I've been arbitrating armed combat against fantastic opponents using 2d6, leveraging the following:
| To Hit Armor Class | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Attacker Tier | <2 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9+ |
| I | 11 | 10 | 9 | 8 | 7 | ||||
| II | 10 | 9 | 8 | 7 | |||||
| III | 10 | 9 | 8 | 7 | |||||
| IV | 9 | 8 | 7 | 6 | |||||
| V | 9 | 8 | 7 | 6 | |||||
Player characters advance, as normal, according to class and level, maintaining compatibility, as close as feasible:
| Tier by Level Range | |||||
|---|---|---|---|---|---|
| Class | I | II | III | IV | V |
| Fighting Man | 1-3 | 4-6 | 7-9 | 10-12 | 13-15 |
| Cleric / Thief | 1-4 | 5-8 | 9-12 | 13-16 | ~ |
| Magic User | 1-5 | 6-10 | 7-15 | ~ | |
The table could be expanded as far as necessary - 0e provides a mechanism to extrapolate into the 20s - but since adopting this test, the highest level at play is 4, so it seemed premature.
But why?
First, in Chainmail, the Fantasy Supplement is generally assumed to be intended for the Man-to-Man scale: that is, when you were playing a fantasy game, you were using a 1:1 figure scale. In Man-to-Man, attacks are resolved on 2d6, based on the weapon the attacker is using versus the armor the defender is wearing. So as you worked your way across the battlefield - a Superhero may, for example, hack his way across normal infantry according to what he's wearing: rolling up to eight attacks per turn - but once he finishes working his way towards the enemy Troll, he instead rolls a single 2d6. If he succeeds, the Troll is defeated; if the Troll succeeds - he is defeated. As such, if I want to use the Man-to-Man tables in my 0e game, then it logically follows a 2d6 resolution is in line with the spirit of the Fantasy table for my 0e game.
This consistency of resolution mechanic mirrors the Armor vs. Weapon table Gary would provide in the Greyhawk supplement for the d20 based ACS. Gary understood that the unified attack mechanic was easier for players to use and would make for smoother gameplay. If you have multiple attacks and coincidentally have multiple d20s, you can simply roll them all together. Further, while it's easy to add two single digit numbers together, if you are simply reading a number off a single die, that is necessarily smoother and faster at the table, itself. Lastly, from a business perspective - if his game used funny dice while borderline every other game stuck with the d6, the d20 would then be a delineator: a visual and mental distinguishing factor to make D&D stick out from the crowd. So I understand why he went with the d20 - but in the same way he introduced the Weapon vs Armor Class table for Greyhawk to standardize around the ACS, I can also standardize around the 2d6 - conforming the Fantasy matrix to the Man-to-Man: the reverse of Gary's approach.
Second, and more importantly - bonuses and penalties. As anyone with AnyDice is
aware - and as Gary explained in the 1e DMG - any pool of dice (2d6, 3d6, etc)
will have a curve to the result. Depending on your target number, adding (or
subtracting) from the roll will have a likewise different impact:
when rolling
against a target 10 on 2d6, you have about a 1-in-6 chance to hit: if you have
a +2 bonus to the roll, you're suddenly aiming at an 8 instead: about a 41%
chance to hit! That +2 is worth 25 percentage points! Conversely, if you're
rolling against a 6, the difference a +2 bonus makes is 19 percentage points:
up to 91% from 72%.
Of course, 19 percentage points is nothing to sneeze at: but because the way curves work, having smaller bonuses can give significantly larger impact: preventing numbers bloat. Vorpal Sword (+5) cumulative with Strength bonus +5? No thanks.
Lastly, as it pertains to bonuses and penalties, consider also that now - there is no need of leveling the bonuses. If I am using Man to Man in one combat and the original, d20 ACS in the other - my +2 sword from before means more in the former instance than it does in the latter - as a +2 is always 10 percentage points on a d20. The argument has been made that this is a good thing - it makes the d20 easier to predict in the head - but honestly: with a bounded curve with as small a band as 2 to 12? It's not hard to figure out "I usually hit when I have a target number of 6, and its hard to hit once it gets above 8." The vagueness of the gut reaction to a curve produces better immersion - if you know instinctively your exact changes, you then can weigh changes with precision: something that doesn't evoke the same emotion as having a notion of "it's hard to hit, but can I make it?"
Target Number Bands
You'll have noted, also - some numbers are more common than others. Target 9, for example, bands over three armor class ratings in all but the highest of attack tiers.
The reason for this is twofold: first, it corresponds more closely to the probability of the d20 on the corresponding OD&D matrix - preserving compatibility with TSR content - but second: it adds some spice to armor. The player is no longer bound to have the best armor he can afford - of course, heavier armor is generally better, but if he's up against low HD enemies who may be attacking as a Tier I or II, if he can get to a 5, he doesn't see improvement again until 2: which frees him up to either invest in that plate mail or to accept an AC 5 - and with it the reduced encumbrance of that armor: he can swim now and not most assuredly die; he can carry more treasure or more equipment, possibly a second weapon - as some weapons work better in some circumstances in Man-to-Man: in contrast to the ACS, where all weapons are effectively equal. That magic ring that offers armor class? That magic shield? Suddenly Warduke's historically absurd attire makes sense! And we're not in history, after all - we're in pulp sword & sorcery!
So that's what I've been up to.
I hope it's provided something to think about - and maybe it gives you a way to include more Chupacabra in your Chainmail at the same time.
Delve on, readers!






























