Monday, March 16, 2009

Descending Armor Class ....Does ANYBODY still use it?

In my ongoing education toward becoming a game master (dungeon master, referee, labyrinth lord or whichever you prefer), I've been reading my Swords & Wizardry Core Rules book from front to back to be sure I'm not confusing my recollection of the rules I am going to use with tidbits from any of the other RPG systems I've played.

Then I got to the part about Armor Class and how to use ascending and descending AC charts in combat...and felt compelled to thank my lucky stars that our group has always chosen ascending AC whenever we have been offered the choice.

Okay..a quick refresher course in old-school weirdness for those of you who are late coming to the party and can't remember back to the times before there were Feats and when Half-Orcs were only allowed to be monsters.

For some odd reason, back in the early days of The Game We All Know, it seemed like a good idea to let the lack of armour be represented by 9, and the very best magical protection to be represented by a -9.

Uh-huh... less is more.... makes sense to me.

So in the beginning when there was combat, and you were a first level Fighting Person,and you wanted to attack an orc with an AC of 6, you consulted a table and saw that you needed to roll a 13.

Then along came THACO. (That's "To Hit Armor Class 0") in the 2nd edition of The Game We All Know, and suddenly each character had their own special "to hit" number based on what type of character they were and how large their group was. Of course there were tables provided to find your THACO number. Then, when facing an orc with AC 6, all you had to do was take your THACO number and subtract the orc's AC from it to know what you had to roll. This was ..and I'm quoting here.. "speed the play of combat greatly"

Ummm.. oookay... so I subtract... unless of course the orc is armoured like a tank with which case I add...right? Math is haaaard. I'm just a girrrrrrl!

Then somewhere around the end of the last century, some lazy person like myself got the bright idea to flip-flop the AC so that it goes up instead of down as you add on armour, and then to give your character a "Base Attack Bonus" instead of making you consult another table. I mean seriously... if we wanted to consult charts and tables all night long, we'd be playing Bosses & Board Rooms.

Well...getting back to the here and now..and closer to my elusive point...I was reading through S&W Core Rules and came across the bit about ascending and descending...and how you can either use the table as it was intended OR if you choose to use ascending AC, a simple formula..which I will quote.
"Here’s how it’s done: each character class gains
a base “to-hit” bonus as their levels increase. Add this
bonus to your attack roll, and if the result is equal to or
greater than the opponent’s AC, the attack hits."
And somewhere, some poor schmuck is going NOW WHY DIDN'T I THINK OF THAT!

Now I normally consider myself to be just weird enough that I can actually find the bizarre logic behind just about anything, no matter how silly..but this one has me stumped. Perhaps descending AC is legacy rules from some old mothbally tactical historical game that TSR wrote back when TSR used to write such things..or maybe somebody wanted to make the math unnecessarily complicated so that non-nerds would shrink back in fear upon encountering such esoteric arithmatic.

But far be it from me to pontificate about which method of AC numbering is "right" and which isn't. I certainly don't mean to say anybody out there needs to change if they prefer the descending method...but I am genuninely curious as to why.


And for what it's worth, in the two years I played 2nd edition The Game, I NEVER was able to totally wrap my head around THACO. I'd just grin stupidly and allow the DM to tell me how badly I flubbed the attack and to which corner of the room my sword flew from my hand.


Edsan said...

I remember reading an interview with Dave Arneson where he explained the reason of "descending AC" was that it had been imported from some American Civil War naval wargame he had played in.

God knows why the folks who desinged that game used it in the first place.

I use descending AC in my current EPT PbP game because the rules system uses it (dated circa 1975 and ageing :)

I have no problem with the maths but admit ascending AC systems are much more intuitive.

OTOH there is something about the descending AC scale. I think having a 0 and negative ACs right in the middle makes you realise whatever reaches such a good defensive value does so for a reason, usualy magic or the best equipment you can find and quite high DEX.

I remember being baffled by the AC inflation when 3rd edition came out (not the reversed ascending AC system, just the hights if the vaues), finding creatures or characters with an AC of 30, 40 or even 50 my reaction at the time was "What in the hell?!".

taichara said...

I use descending AC (started with 2e, dallied with ascending AC with 3e, went back to 2e, currently running BEMCI).

I like descending AC; I don't find it any more cumbersome than ascending, and -- as Edsan suggests above -- there's something about passing that Rubicon of AC 0 into the negatives that just works for me. Your AC has gotten so special/magical/whatever, now it's a negative number --

And for the record, I'm female and in academia, so it isn't the maths ;3

Spike Page said...

About Arneson's answer, I shouldda known it. And I bet my geeky spouse actually owns a copy of said mothbally ACW naval game..with unpunched counters and still in the shrink wrap.

Somewhere in that game, there is a representation of the CSS Georgia.. Armor Class 9..just ASKIN' to be sunk.

I suppose at the end of the day, we all go with what we know best. What makes it fun is having to juggle so many systems at once. And to add one more loose wrench into the machinery, my friend Codename:Unglef is about to start our group out on a Pathfinder campaign.

PLEASE tell me the AC system doesn't change again.

Anonymous said...

I'm more used to descending AC -- but I don't like the math either! I think I'm the only person who actually likes using the to-hit charts in the books + screens instead of doing the math to figure out what you need to roll to-hit. :)

Sham aka Dave said...

When I converted my old 1E descending AC games to a homebrewed version of ascending AC, the effect was not faster play as I had hoped. The players never took to it so I am back with standard descending AC. I prefer the modern "attack/defense" system with no tables, but I use OD&D descending now. My players grew up with 1E and it's not a big stretch for them.

One thing that's interesting about the OD&D AC 9-2 tables is that each number is in fact a code detailing the type of armor worn by the player character. In other words, there is only one way to have AC 5. Chain = AC 5 and AC 5 = Chain. Modifiers to AC do not alter that code, they subtract from the attacker's roll to hit! :-)

Christopher B said...

"Descending Armor Class ....Does ANYBODY still use it?"

Um, yeah... and I still use THAC0, as well.

For the life of me, I will never understand how using THAC0 is any harder than adding and subtracting modifiers to determine a result vs. ascending AC. I mean, they're both just simple addition and subtraction. :P

Actually, THAC0 only involves subtracting the target's AC, which is even easier in my book. Maybe it's the idea of subtracting negative numbers that's caused the disconnect? I mean, I'm no math geek, but it never bothered me. (I liked it a heck of lot more than consulting tables, or even using my nifty To-Hit Wheel that I cut out of a Dragon magazine...)

I guess this position makes me 01d Sk001. :P

Joshua Macy said...

Look, it's easy: you roll a die, you add the monster's armor class, and if you get >= your THAC0 you hit. It's exactly the same operations as you roll a die, you add your bonuses, and if you get >= the monster's AC you hit. And since, as has already been pointed out, the player could tell the AC to add just by what the opponent was wearing, you could determine hit or miss without having to quiz the GM each time.

The only reason you'd ever have to subtract is if the GM was trying to conceal the AC of a creature he made which case blame the GM, not the AC rules.

Unfortunately, later editions made it a bit more unwieldy, by having a bunch of factors that could adjust AC up or down so it didn't strictly map to armor any more...but as long as the GM would announce the AC of the target it was still just as easy as ascending AC.

Anonymous said...

The thing to remember, I think, is that originally there was no such thing as negative armor classes. The best armour in the whole world was AC 2. Originally, bonuses from dexterity, from magic, etc, maxed out at around +1, so if you were really, really lucky, your Plate & Shield fighter might have an AC of 0 as the best possible AC anyone could ever have.

And with that limitation, the system makes sense, because you just add your roll to the AC, and if the number is over the THACO, you hit.

Gamma World first or second edition used the AC 10= naked, ac 0= super duper armour, and actually mandated that no character or creature could ever have an AC better than 0.

Jack Badelaire said...

Also consider the following:

* 3.X was built on a unified mechanic. You ALWAYS roll d20 + mod vs. Target Number, if(result >= TN) you succeed. This is not just "swap ACs around cuz maths is harrrd" - it is a complete design overhaul of the system. People who crap on those who like ascending ACs because "they can't handle the math" piss me off.

* D&D itself was never consistent with it's nomenclature when using descending ACs and it was always a real pain in the ass. When magical suits of armor and shields had +'s on them, this didn't make it worse, even though adding a number to the AC would do so - you...subtract...the bonus? The language was always just cumbersome - "bonuses", "improvement" etc. all point to "adding" to a value in some parts of the game, while pointing to "subtracting" from a value in other parts.

Frankly, I say, good riddance. I am happy to use descending ACs when I am playing an older edition, and I do believe that someone of reasonable intelligence who puts reasonable effort into figuring out the rules can "get" it and all the other wonky rules...but from a design standpoint, I think it's crap.

But, I guess that means I'm a 3tard and have no soul, or something...

Joshua Macy said...

Negative AC is the same as positive AC: add the AC to the roll and see if it's >= THAC0. I don't really get how some people claim that 17 + -2 = 15 somehow hurts their brain, but never seem to have trouble with 17 + 2 for DEX, + 2 for magic Sword, -1 for dim lighting, +3 for being a favored enemy....

Chad Thorson said...

I don't think THAC0 is too hard, or the ascending/descending system. But a more streamlined approach is always better in my book! I like your approach, and I was coming up with something similar, because it just made sense to me.

Wayne Rossi said...

I use descending AC.

It's not hard or anything. It's simply a matter of habit - if AC 7, 5, 3, and -1 didn't mean definite things in my head I could consider going to an ascending system. As it is, most of the rulebooks, supplements & such that I enjoy are written with descending AC. When I ran Castles & Crusades it had ascending AC, and I didn't like it aesthetically. Just wasn't for me.

Will Mistretta said...

I would never, ever use anything else. It's all about the flavor of classic D&D to me. Ascending AC just looks all wrong and feels all wrong. It also invokes WotC's so-called D&D designs, which is just adding insult to injury.

I personally believe that it's vital to the authenticity of any true "old-school" D&D movement to embrace the classic rules as they were, and refrain from trying to re-invent any wheels.

The rules are fine. Always have been, always will be. Better to get to work on the campaign worlds, new monsters and magic, dungeons, and other novel uses for them.

Spike Page said...

Wow... lots of responses here..and some pretty strong opinions too. It seems that for some it is simply the way they learned it..for others has become a point of identification with what's old-school..and for some, ..well... it's just not for some of us..myself included.

This all reminds me of the metric system..a topic which often starts heated debates in this household. The idea of basing my system of measurement upon the size of some dead king's foot is right laughable..but to my husband, "it ain't why fix it." For what it's worth, while I find "my way" to be better for me, there is much that can be said for being able to work with either system...even if I get chided for pronouncing it wrong.

So... is it THACO with a long "a" as in "grey"...or..umm..I mean "gray"...??

Jack Badelaire said...

Not to defend the metric or Imperial system, but one reason the Imperial is still around is that inches, feet, and yards (and their divisions) work better for carpentry and construction. 12 is a much more easily divisible number than 10 - you can cut it in half, in thirds, in quarters, and even in sixths (or, well, 12ths) and not have to worry about fractions. Many construction / contractor type people I have talked to over the years simply find it more flexible to use and get "clean" numbers, especially when working with geometry and angles.

Edsan said...

Indeed. I come from a metric country and had to learn Imperial to play D&D properly. At first it looked silly but then I realised there is something much more organic to it than the neat 1:10 proportions of metric, and descriptions of monsters and visual distance work better when you use imperial.

And I don't get why people get their kickers twisted so much about this issue, it's not like mastering the two systems required a supreme effort of will.

trollsmyth said...

Descending AC here, though part of the appeal of my current Labyrinth Lord game is the "old school" feel.

I don't really use THAC0 (which I've always mispronounced "THAY-koh") either. I use charts. Which is admittedly a touch slower but does allow me to do cool things like my rogue's funky to-hit table.

Dwayanu said...

I use descending AC because I referee the original D&D game, and that's what's in the monster descriptions and on the combat charts.

The charts make the difference. Classes could just as well be alphabetical, because I'm not doing arithmetic with each roll!

For me, that's convenient and fast-playing.

Dwayanu said...

Historical Note: The 9-2 system is derived from the 1-8 system of Chainmail, which Gygax (not Arneson) co-authored. IIRC, the key elements Arneson added from naval rules were hit points and "critical hits."

The Chainmail man-to-man tables have leather before shield, and incorporate weapon-versus-armor type considerations directly into the numbers (2d6, roll high).

It's possible that at some point the Blackmoor campaign used a roll of 2d6 vs AC (roll low), which would make the 9-2 (lower=better) range directly useful. It would also make plate & shield very hard to hit!

Perhaps the (fairly simple) tables in OD&D, because they're representing data in the more primal visual form (rather than in the abstract of equations), more readily wear paths to instant recognition/subconscious evaluation in at least some brains.

Jeffrywith1e said...

I always thought THAC0 would've been a cool personalized license plate.

S. John Ross said...

I still use it when I run D&D, sure. Them's the rules in D&D [not to be confused with the game published by WotC under the same legal trademark ... no relation].

The other games I run don't have Armor Class, so I don't use it then.

Spike Page said...

And yep..I was right.

My husband INDEED owns Ironclads, the original descending-AC beastie.

FWIW he's pretty darn old-school. I'd feel safe to say he was already playing D&D when I was still playing Candyland (and no, that wasn't just last week either)

But he and I both agree about AC, and prefer ascending.

DMWieg said...

Yes, we use it when we play older versions of D&D/AD&D or one of the so-called retro clones.

Descending Armor Class and THAC0 are a little wonky, but they're what I grew up with. I remember being surprised by the ascending AC system in Gamma World 4th edition, which is the first time I ever saw such a thing. Instead of having Base Attack Bonus, it had the "THAC" bonus. (Which was pretty much the exact same thing)
Ah, memories.

noisms said...

Once you get the hang of descending AC it's actually easier than ascending, in my opinion. It's to do with when you do the arithmetic: before or after you roll.

Matt Finch said...

I think it depends on whether you like or dislike charts. If you like using charts, then the absolute numbers are smaller using a descending system, which is nice. If you prefer using a formula, then I think the ascending AC system tends to work better (and eliminates +2 shields that actually reduce your AC, etc).

I think a lot of it has to do with what you started with, but I started with descending AC and prefer ascending AC, so it's not entirely that.

John said...

Simple: I use descending AC in D&D, and ascending in 3rd edition

Smokestack Jones said...

I use descending AC for a couple reasons:

1. It's what I learned and I'm old.

2. Most old supplements use descsnding AC and I'm too lazy (i.e. old) to convert the damn AC.

I also use THAC0. It's easy: Roll a D20 and subtract it from your THAC0. That's the AC you hit.

It also works for ascending AC - simply add your die roll instead of subtracting it.


Eponymous said...

The Combat Roll
Roll 1d20...
+ target’s Armor Class
+ attacker’s Combat skill
+ attacker’s attribute modifier
+ attacker’s Attack Bonus
If the total is 20 or greater then the attack hits. A
natural roll of 1 always misses, and a natural roll
of 20 always hits.

Eponymous said...

PS - Mathematically its all the same thing just moving the values around. So you know just use what you like