Older D&D/AD&D and Other SystemsThe forum for discussions specifically related to the rules and procedures of either any of the older editions of Dungeons & Dragons (1e, 2e, BECMI, OD&D) or any other non-D&D roleplaying rules (Vampire: The Requiem, Dread), including non-fantasy d20 systems (such as Mutants & Masterminds).
A couple of the D&D articles i've read lately were written in a 2nd edition paradigm, i've not played that version of the game. but from Wikipedia I gather that THACO was the 1st and or 2nd ed equivalent of a BAB, armour class was the other way around and you subtracted your opponents AC from your THACO to determine what number you needed to roll to hit?
this seems a bit counter intuitive to me (although, it could just be that i'm so used to the BAB and positive AC conventions of 3/4 ed games.) so i'm wondering how this came about? did it evolve from some earlier system or convention in the earliest versions of D&D or in the wargames that preceeded it.
so yeah, basically
A) have I got this right?
and
B) from a game design view point how did it come around ?
__________________
Time is but a pattern in the currents of causality,
an ever changing present that determines our reality,
the past we see as history, the future seed with prophecy,
and all the time we think on time our time is passing constantly.
A couple of the D&D articles i've read lately were written in a 2nd edition paradigm, i've not played that version of the game. but from Wikipedia I gather that THACO was the 1st and or 2nd ed equivalent of a BAB, armour class was the other way around and you subtracted your opponents AC from your THACO to determine what number you needed to roll to hit?
this seems a bit counter intuitive to me (although, it could just be that i'm so used to the BAB and positive AC conventions of 3/4 ed games.) so i'm wondering how this came about? did it evolve from some earlier system or convention in the earliest versions of D&D or in the wargames that preceeded it.
so yeah, basically
A) have I got this right?
and
B) from a game design view point how did it come around ?
You have it pretty much right. Instead of your target's AC being the target number, with your roll modified by your BAB, To Hit Armor Class 0 is the target number, modified by your opponent's armor class. It's neither easier or harder, just reversed.
Which kind of answers B; you're still taking a target number and adding a modifier, so it's not really that different.
did it evolve from some earlier system or convention in the earliest versions of D&D or in the wargames that preceeded it.
Yes. It's a hold-over from previous editions. In those days, armor was rated by class. So the best armor was 'first class,' (AC 1), the second best armor was 'second class' (AC 2) and so on, all the way down to the worst armor, 'tenth class' armor, or AC 10. Thus, the lower the number, the better the armor, and thus THAC0.
__________________
The problem with the more recent editions of D&D is that at some point the term 'player empowerment' was twisted to mean 'player entitlement.'
The way I learned Thaco was that you take your roll, add the armor class of the target, and see if it is greater than or equal to your Thaco.
Roll + AC >= Thaco to hit
Roll + AC < Thaco is a miss
ex: Thaco of 17, enemies armor class is a 4
You want Roll + 4 to be greater than or equal to 17, so a 13 and up hits.
Of course, factor in other modifiers as they come up.
If it really confuses you, you could always just reverse it, 20 - thaco = base attack, so a thaco of 17 is a +3 base attack bonus. Then you just reverse AC so it ranges from 10-30 instead of -10-10. The 4AC from our example above would become a 16 then.
Originally you had a table with level going down one side and armour class across the other showing target numbers. For some reason between Chain Mail and Dungeons & Dragons armour class was reversed. The reason remains a mystery, though many interesting theories abound (such as percentages using the 2d6 system on a 2-12 scale before polyhedron dice) but Gygax was responsible for the change. Likely he thought that AC 1 was a "first class" armour value.
THAC0 is basically the target number, for instance:
1D20 + AB + AC > 20
becomes:
1D20 + AC => THAC0
In the DMG (1979) Gygax notes that he chose to keep descending AC for continuity with the original game (1974).
__________________ It is a joyful thing indeed to hold intimate converse with a man after one’s own heart, chatting without reserve about things of interest or the fleeting topics of the world; but such, alas, are few and far between.
– Yoshida Kenko (1283-1350), Tsurezure-Gusa (1340)
I usually did it as THAC0 - 1d20 = AC hit, so I could report the latter number without necessarily having to know what my target's AC was.
I honestly find this easier than adding 1d20 + attack bonus to determine AC hit. Mostly because the numbers involved tend to be smaller, I think. Neither of them are particularly difficult, though. 3.x's messiness comes in because there's so freakin' many fiddly situational modifiers to keep track of.
Switching back and forth hurts my brain, though. I was playing 3.5 on Thursday nights and AD&D on Saturdays for a while there, and I never knew what the hell I was doing for the first fight of a session.
__________________
Play your character, not your alignment.
I wouldn't call THAC0 intuitive. When you're used to it, you can do the calculation as fast as you would be able to calculate it using BAB.
But if you explain BAB to a completely new player, he'll instanly understand "1d20 + BAB = AC" means a hit.
If you explain THAC0 to a new player, the initial reaction I've always experienced is a mix of a blank stare with some slight terror in the eyes, mixed with some doubts that it was a good idea to learn this game.
But BAB you understand instantly with no confusion. That's more what I think of as intuitive.
The random background generator is awesome. I got a NG dwarven magus who was involved in a "pleasure" scandal with some arcane experiment backfire as well. My imagination is running off with that.
There is an explanation issue with THAC0 (it is a weird acronym for one thing), but it is purely a matter of language used. If you say, for instance, "THAC0 is the target number you need to hit an opponent, the base difficulty goes down as your character goes up in level and you get +10 to hit an unarmoured foe" it seems pretty straightforward and intuitive.
__________________ It is a joyful thing indeed to hold intimate converse with a man after one’s own heart, chatting without reserve about things of interest or the fleeting topics of the world; but such, alas, are few and far between.
– Yoshida Kenko (1283-1350), Tsurezure-Gusa (1340)
“Not a promise, not an oath, or a malediction or a curse,” I said, sounding calm, probably inaudible in the midst of the screaming. “Inevitable. Wasn’t that how she put it? I told them. Warned them.”
-Taylor Hebert. Yes, I'm a proud Skittle.
ah , the first class and second class armour makes a lot of sense. I figured there must be something like that.
so generally does the DM tell the players their opponants AC up front? rather than letting them work it out as the fight progresses? I can see it being a lot harder to work out whether you hit or not if you don't know the AC with this system.
__________________
Time is but a pattern in the currents of causality,
an ever changing present that determines our reality,
the past we see as history, the future seed with prophecy,
and all the time we think on time our time is passing constantly.
ah , the first class and second class armour makes a lot of sense. I figured there must be something like that.
so generally does the DM tell the players their opponants AC up front? rather than letting them work it out as the fight progresses? I can see it being a lot harder to work out whether you hit or not if you don't know the AC with this system.
Not necessarily, if you subtract your hit roll from your thac0 you get the AC that you will hit. It is slightly harder in that you have to subtract instead of add, but subtraction isn't exactly rocket science. Also, as was mentioned before you have fewer situational so that makes it easier.
Honestly, the easiest we discovered was to just write a 2 column table on you character sheet--if the dice is this I hit an AC of that. Not that subtraction is hard, but any math can slow down combat.
__________________
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
--Will S.
How do you pronounce Thac0, by the way? Tack-zero? I know I've met people who pronounced it Taco, like the mexican food, but that's a bit weird too.
Quote:
Originally Posted by raitalin
Everyone I've know has either prnounced it thay-co or tha-co.
Apparently, Tim Kask pronounces it the former way, and Frank Mentzer the latter. So basically no consensus even amongst former TSR company employees of the late 70s and early 80s.
Quote:
Originally Posted by EccentricCircle
ah , the first class and second class armour makes a lot of sense. I figured there must be something like that.
so generally does the DM tell the players their opponents AC up front? rather than letting them work it out as the fight progresses? I can see it being a lot harder to work out whether you hit or not if you don't know the AC with this system.
Probably the easiest way to it is have the player roll the die, add the known modifiers (such as strength), and then announce the result. The game master then adds any hidden modifiers (such as armour class) and compares it to the THAC0 of the character. Deducting armour class from THAC0 is the "official" methodology in second edition, which was an odd design decision.
__________________ It is a joyful thing indeed to hold intimate converse with a man after one’s own heart, chatting without reserve about things of interest or the fleeting topics of the world; but such, alas, are few and far between.
– Yoshida Kenko (1283-1350), Tsurezure-Gusa (1340)
Probably the easiest way to it is have the player roll the die, add the known modifiers (such as strength), and then announce the result. The game master then adds any hidden modifiers (such as armour class) and compares it to the THAC0 of the character. Deducting armour class from THAC0 is the "official" methodology in second edition, which was an odd design decision.
And sometimes the simplest solution for all the "confusion" was to either have the players write out a one or two line chart detailing what roll they need to hit which armor class, or for the DM to just reconstruct "to-hit tables" on his end and just go from there. Roll a D20, add modifiers, and tell me what you got and I'll tell you if you hit.
First of all, I pronounce it THAY-co. Always have.
Secondly, as Matthew mentioned, everyone character sheet I ever made had a doodle on it. It was was
Roll AC
20 -1
19 0
18 1
17 2
16 3
15 4
usw. It included all my standard mods (like a strength bonus), but not weapon-specific modifiers (like a +1 sword). Thus, I rolled a die, added a bonus for the weapon, and knew the number. In many ways, this was easier than the 3e version, because the numbers were always pretty small... I had to add something like 1-5 to a given number and consult a simple chart, rather than the marginally harder add two numbers of two digits each.
__________________ The Cranky Gamer
*It isn't realism, it's verisimilitude; the appearance of truth within the framework of the game.
*"My Little Pony" is the name of my Wyld Stallyns cover band.
*"I'll give you a hint. It begins with 'L', ends in 'd', and has an 'awful goo' in the middle."
*Since I'm bound to mention it and you're bound to ask: C&C stands for Castles and Crusades.
Avatar is from Thunt's Goblins! HackMaster Basic: A Free Game
so generally does the DM tell the players their opponants AC up front? rather than letting them work it out as the fight progresses? I can see it being a lot harder to work out whether you hit or not if you don't know the AC with this system.
No. Like I said, THAC0 - 1d20 gives you the AC that you hit, and you can just call out that number and the DM can apply any modifiers you don't know about, compare to the target's AC, and tell you if you hit.
It's exactly equivalent to 3.x's system, except you subtract 1d20 from your THAC0 instead of adding 1d20 to your AB.
And, like I said, I find it slightly easier to do, "Okay, my THAC0 is 8, I rolled a 13, 8 - 13 == -5, 'I hit AC -5,'" than, "My AB is 18, I rolled a 13, 18 + 13 == uh, 11, carry the 1, 31, 'I hit AC 31.'"
And that's even before getting into the, "But -2 for Rapid Shot makes it 29, and -3 for Deadly Aim makes it 26, and I'm getting my favored enemy bonus, so 30, but I've been strength-drained, so I'm at -2 because my magic bow can't adjust to changes in my strength for some ridiculous BS reason, so 28. Oh, wait, is that 30'? 5, 10, uh... 20?, 25... yeah, I guess so. +1 from Point Blank Shot... crap, I forgot what I had before I started counting distance. 18 + 13 is..."
(This exactly how my last fight went. For four attack rolls per round, not all of them at the same attack bonus. My turns got a lot faster when the DM actually told me what the shadows' AC was, and I was able to determine that even for my last iterative I just needed to not roll a 1.)
__________________
Play your character, not your alignment.
And sometimes the simplest solution for all the "confusion" was to either have the players write out a one or two line chart detailing what roll they need to hit which armor class, or for the DM to just reconstruct "to-hit tables" on his end and just go from there. Roll a D20, add modifiers, and tell me what you got and I'll tell you if you hit.
Certainly. I was thinking the easiest way to figure the number, rather than to look it up, of course.
__________________ It is a joyful thing indeed to hold intimate converse with a man after one’s own heart, chatting without reserve about things of interest or the fleeting topics of the world; but such, alas, are few and far between.
– Yoshida Kenko (1283-1350), Tsurezure-Gusa (1340)
The Thac0 (thack-o) system is really much simpler then all this AB + BC(BAB) times pi nonsense. The math degree was not required until the later editions.
The Thac0 progression was based on class, warriors advancing quickest because they are used to pummeling beasties.
For example all first level cahracters started with an unmodified Thac0 of 20. You would have to roll an unmodified 20 to hit some one with AC 0. Any modifiers would be applied to your Thac0. A +2 to hit would give you a Thaco of 18.
In the earlier editions the lower your armor class the harder you were to hit, thus a higher roll was needed.
Most character sheets hads a Thac0 chart that looked like this
(filled in with a 20 Thac0)
AC: -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
Thac0: 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
Modifiers would move the bottom numbers like a sliding scale. No deducting AC or any of that just a static AC line and a sliding Thac0. If you had +2 your Thac0 would be 18 and 18 would be under the 0 on the Thac0 number line.
Easy peasy. No complicated equations or algorhythms to figure out. Made combat much faster than my later edition expirences. Though I must admit I am biased to 1st and 2nd edition. There was more fantasy, and less buff configuring MMORPG power gaming.
Put me in the camp of never understanding why people couldn't understand THAC0. I mean, I figured it out how to do it in High School, but then I was a Math/Science Geek...
We always pronounced it "Thay-Co" unless we wanted to be funny and say, "Thwack-O"...
I had an idle thought, and haven't bothered to work the math out on this...
But after reading through Bounty Head Bebop's "inverted 20" system, where you try to "roll under" your attribute scores, I was struck with this thought. Would it be possible to alter something in the THAC0 system, so that you were using a roll-under mechanic? Would this possibly make it easier to compute on-the-fly?
I have no real reference to compare the attack mods. for third edition since i haven't played it in about ten years, but i do love 2E and thats the only system most of the people I play with know. (Plus our DM has been running an epic campaign thats taken us a few years to get to the halfway point, and he created this one pre 3E.) But back to THAC0 depending on the situation there is quite a few mods to consider, for starters depending on the weapon type you might use your DEX mod instead of STR, e.g. a bow or other missile attack would call for a Dex mod and almost all melee use Str as the mod. Plus as Max mentioned any individual weapon bonus has to be counted for. And you can't forget 2E has weapon proficiencies so you had a bonus to THAC0 if you could specialize and depending on your class your THAC0 got worse if you tried a weapon you didn't spend a proficiency slot on(Warriors had the smallest penalty). But like any system the longer you use it the the easier it gets to use, but as i said its been so long since i even looked at 3E that my memory of the mods and such are hazy at best...
Put me in the camp of never understanding why people couldn't understand THAC0. I mean, I figured it out how to do it in High School, but then I was a Math/Science Geek...
Yeah, seriously, I was playing with it in 3rd grade. It's just subtraction. It's not hard.
Of course, I've found that a lot of the college kids I've been gaming with lately can't add single-digit numbers without counting on their fingers...
Quote:
We always pronounced it "Thay-Co" unless we wanted to be funny and say, "Thwack-O"...
My groups have mostly pronounced it "thack-oh", but I've run into a couple of "thay-co" sayers.
Quote:
Originally Posted by Elyssian
I have no real reference to compare the attack mods. for third edition since i haven't played it in about ten years, but i do love 2E and thats the only system most of the people I play with know. (Plus our DM has been running an epic campaign thats taken us a few years to get to the halfway point, and he created this one pre 3E.) But back to THAC0 depending on the situation there is quite a few mods to consider, for starters depending on the weapon type you might use your DEX mod instead of STR, e.g. a bow or other missile attack would call for a Dex mod and almost all melee use Str as the mod. Plus as Max mentioned any individual weapon bonus has to be counted for. And you can't forget 2E has weapon proficiencies so you had a bonus to THAC0 if you could specialize and depending on your class your THAC0 got worse if you tried a weapon you didn't spend a proficiency slot on(Warriors had the smallest penalty). But like any system the longer you use it the the easier it gets to use, but as i said its been so long since i even looked at 3E that my memory of the mods and such are hazy at best...
Yeah, but all of those are fixed modifiers. You can figure them all into your THAC0 beforehand and just record the modified THAC0 on your character sheet alongside the individual weapon, along with its damage numbers and other vital statistics.
3.x has all of that stuff and more, plus it much more commonly adds in situational modifiers that don't always apply and so can't just be pre-figured as part of the attack bonus for a given weapon.
My current 3.P character, for example, has a +10 BAB. BAB - Base Attack Bonus - is the equivalent of the AD&D basic THAC0 determined by class and level, and a +10 is equivalent to a THAC0 of 10.
3.x characters also get extra "iterative" attacks based on their BAB, with every 5 points of BAB giving you another attack, at a cumulative -5. So I get one attack with a +10 BAB, and a second with a modified +5 BAB. Next level, my BAB goes up to +11, and I get additional attacks at +6 and +1.
Then to that BAB, I apply those other, weapon-dependent, modifiers... Str or Dex, weapon enchantment or masterwork bonus, non-proficiency penalty (rare... 3.x proficiencies are coarser-grained than AD&D, so as a martial class, I'm proficient in all simple and martial weapons, and get the non-proficiency penalty only on a few exotic weapons, the only one of which I carry is a bola, which I've never actually used), and other random bonuses like my +2 with bows from my greater bracers of archery, which gives me a weapon-specific attack bonus, equivalent to the modified THAC0 that I'd record for each of my weapons in AD&D.
Add all those modifiers in, and I end up +18/+13 with my bow, which is my primary weapon. But on top of that, I have various feats, combat maneuvers, and other situational modifiers that may or may not apply. All of that stuff that I was adding and subtracting in that example in my last post? That's all stuff I really have to worry about with my actual character.
Rapid Shot is a feat that I can decide to use or not, which gives me an extra attack at my best BAB, but applies a -2 to-hit penalty to all my attacks. It may or may not be a worthwhile trade, depending on my target's AC, so I don't always use it.
Deadly Aim is another feat that I can decide to use or not, which gives me straight-up bonus damage on all my ranged attacks in exchange for another to-hit penalty. Again, depending on the target's AC, it may or may not be worth it.
Point Blank Shot gives a +1 bonus to hit and damage against targets within 30', so I don't decide whether to use it or not, but I have to count up ranges to figure out whether or not it applies. If I switch targets in mid-volley, it may apply to some targets but not to others.
Favored Enemy is a Ranger class feature that gives me bonuses to hit and damage against certain creature types... I get +2 against orcs and +4 against undead. Next Ranger level I'll get to add another one, and will probably be going with another +4 against humans. Again, not one I decide whether to use, but that may or may not apply depending on what I'm shooting at.
We have a cleric in the party who frequently throws around buff spells that give small bonuses to hit, too.
And then there are other situational modifiers, like trying to shoot my exceptional-Strength bow when I've had 10 points of Strength drained by shadows is a -2 to hit.
There's a -4 "shooting into melee" penalty and another -4 penalty for shooting at a target with cover that frequently apply, but I fortunately get to ignore those because of other feats that I have (Precise Shot and Improved Precise Shot, respectively).
There's a -4 penalty for shooting while riding a mount that's moving faster than its single-movement, and a -8 penalty for shooting from a mount that's running, and another feat (Mounted Archery) to cut those in half, which I don't have because it's so not worth it when my mount's single move is 80' anyway.
Archery is pretty bad about the situational modifiers, but melee isn't much better. With my saber, for example, I've got the usual BAB, Str modifier, and enchantment bonus, which puts it at +16/+11. But then, if I rage, my Strength goes up, which affects my Str modifier and thus my to-hit bonus from it, and I get an effective +2 to hit with my melee attacks. If I'm mounted, I get a +1 to hit with my saber that doesn't apply when I'm on foot. If my target is smaller than my mount, I get another +1 on top of that. If I charge (or my mount charges), that's a +2 to hit. If I'm flanking my target, I get an additional +4 to hit (but my dire wolf mount only gets a +2 from flanking... my flanking bonus is higher than usual because of a Barbarian alternate class feature I took). My favored enemy bonuses all apply to melee, too. Deadly Aim doesn't apply, but there's an equivalent feat for melee called Power Attack, which I don't have yet but will in a few levels. (And in Pathfinder, the Deadly Aim and Power Attack bonuses and penalties are fixed to your BAB, but in vanilla 3.5, Deadly Aim doesn't exist, and Power Attack is variable, allowing you to take any penalty up to your full BAB and getting a damage bonus based on that.) There's a +4 bonus for attacking a prone target, which I fairly often get because my wolf gets free trip attempts when his attacks hit. Cover modifiers can sometimes apply to melee attacks, too (though rarely), and Improved Precise Shot doesn't let me ignore it for melee. And all those cleric buffs and stuff apply to melee as well...
__________________
Play your character, not your alignment.
Yeah, but all of those are fixed modifiers. You can figure them all into your THAC0 beforehand and just record the modified THAC0 on your character sheet alongside the individual weapon, along with its damage numbers and other vital statistics.
3.x has all of that stuff and more, plus it much more commonly adds in situational modifiers that don't always apply and so can't just be pre-figured as part of the attack bonus for a given weapon.
Good to know, i've been wanting to learn a bit more about the newer editions lately as my brother wants to run a short pathfinder game for our group this summer and its going to be a whole new world for most of us, and it will give our DM a chance to sit back and play for once. Although i can bet on us having to draw out a diagram or something with all the new mods so that by our powers combined we won't run off our DM after questioning if we hit after every roll
this makes sense. thankyou to everyone who has explained.
I'm now thinking it will be interesting to play AD&D at some point.
__________________
Time is but a pattern in the currents of causality,
an ever changing present that determines our reality,
the past we see as history, the future seed with prophecy,
and all the time we think on time our time is passing constantly.
this makes sense. thankyou to everyone who has explained.
I'm now thinking it will be interesting to play AD&D at some point.
AD&D is a lot of fun partly due to the holes in the game. You will find that the DM will be making up rules to handle stuff on the spot since the rules were not as complete in some areas (like social interactions).
Yeah, but all of those are fixed modifiers. You can figure them all into your THAC0 beforehand and just record the modified THAC0 on your character sheet alongside the individual weapon, along with its damage numbers and other vital statistics.
3.x has all of that stuff and more, plus it much more commonly adds in situational modifiers that don't always apply and so can't just be pre-figured as part of the attack bonus for a given weapon.
<...Snip...>
This doesn't sound like a problem of THAC0 vs BAB.
Yes, the editions which feature ascending-attack-bonus/ascending-AC/ascending-die-roll do also list more situational modfiers than the editions which use THAC0 (i.e. descending-attack-value/descending-AC/ascending-die-roll).
But this is not inherent to those mechanics.
__________________
If a tree falls in the forest and the PCs aren't around to hear it... what do I roll to see how loud it is?
RSS Feeds: 
Thac0?
