Guyr Adamantine wrote:Nobody here has trouble understanding THAC0. We have trouble understanding the logic behind it.
Tell me: Why add, keep and defend so aggressively such an unnecessary part in the game? At the moment, its only purpose is to inflate your own ego as new players get confused learning the game. Continue that way, and you'll manage to fuck over earth's gravity center.
Well I just searched the 7 issues of The Strategic Review, as well the first 252 issues of Dragon Magazine and saw not a single question about why use THAC0....
So you want the logic behind it? I can only give you my interpretation since Gary and Dave have passed and only have my own intellect and knowledge of many games to base the reasoning behind. So it will be subjective.
Red Box set:
To swing at the monster, you must make a Hit Roll. Roll the twenty-sided die. If you roll an 11 or less, your character misses the goblin. If you roll a 12 or higher, you hit!
Seems like an easy system for Basic (Mentzer set).
Why did it change?
Rules Cyclopedia:
An attack roll is a number representing how easy or difficult it is for your character to hit other targets.
In combat, when your character is trying to hit another character, you roll 1d20; this is known as his attack roll. (In some game supplements, it's also called the "hit roll," "to-hit roll," or "roll to hit.") Once you know the number you've rolled on the die, you add any bonuses your character gets from high ability scores, magical weapons, or other factors. You'll compare that final result to the number required to hit the armor class of your character's opponent. If you reach or exceed that number, your character has successfully hit his opponent.
But how do you find out what number you need to hit a certain armor class? That's simple enough: We provide it to you on handy tables. Take a look at the Attack Rolls Table on page 106.
This is a few years after 1st editoin and collects all the D&D rules together, but it uses tables to tell whether you hit. Still not that hard, compare two numbers and roll >= the number shown where the row and column meets.
1st edition AD&D:
Your DM has matrices for each class of character by level groups, showing the scores required to hit the various sorts of armor and armor classifications. Normal men such as men-at-arms are always considered at level 0. Monsters are classed by their hit dice.
The PHB doesn't tell how to attack? This is a new game so there must be a reason for it. Again RC was printed AFTER 1st edition AD&D. Guess the players just need to do what the DM says to attack and not have to worry about all those matrices. (Thank you Neo!)
DMG:
Using The Combat Tables:
Find the level of the attacker on the appropriate chart and matrix that with the armor class of the defender. The resulting number or greater must be rolled on a d20 for a successful hit. Penalties and bonuses may modify either the die roll or the number needed to hit, as long as one method is used consistently.
So it is the same for RC. Look up the attacker on the proper group (warrior, priest, thief, mage), and look over to the AC of the creature, and add modifiers and compare the modified die roll with the modified number listed on the table.
Seems easy enough still.
That part I made red seems kind of interesting....
A consistent method to use these tables huh?
2nd edition AD&D:
Figuring the To-Hit Number
The first step in making an attack roll is to find the number needed to hit the target. Subtract the Armor Class of the target from the attacker's THAC0. (Remember that if the Armor Class is a negative number, you add it to the attacker's THAC0.) The character has to roll the resulting number, or higher, on 1d20 to hit the target.
Rath has reached 7th level as a fighter. His THAC0 is 14 (found on Table 53), meaning he needs to roll a 14 or better to hit a character or creature of Armor Class 0. In combat, Rath, attacking an orc wearing chainmail armor (AC 6), needs to roll an 8 (14-6=8) to hit the orc. An 8 or higher on 1d20 will hit the orc. If Rath hits, he rolls the appropriate dice (see Table 44) to determine how much damage he inflicts.
The example above is quite simple--in a typical AD&D game combat situation, THAC0 is modified by weapon bonuses, Strength bonuses, and the like (the next section "Modifiers to the Attack Roll," lists the specifics of these modifiers). Figure Strength and weapon modifiers, subtract the total from the base THAC0, and record this modified THAC0 with each weapon on the character sheet. Subtract the target's Armor Class from this modified THAC0 when determining the to-hit number.
Rath is still a 7th-level fighter. He has a Strength of 18/80 (which gives him a +2 bonus to his attack roll). He fights with a long sword +1. His THAC0 is 14, modified to 12 by his Strength and to 11 by his weapon. If attacking the orc from the earlier example, Rath would have to roll a 5 or higher on 1d20 in order to hit (11-6=5). Again, table 44 would tell him how much damage he inflicts with his weapon (this information should also be written on his character sheet).
The DM may also throw in situational modifiers, (for example, a bonus if the target is struck from behind, or a penalty if the target is crouching behind a boulder). If the final, modified die roll on 1d20 is equal to or greater than the number needed to hit the target, the attack succeeds. If the roll is lower than that needed, the attack fails.
Copyright 1999 TSR Inc.
Copied and pasted from its section from the AD&D Core Rules 2.0 Expansion CD-ROM with the copyright notice intact, same as below.
Calculating THAC0
To make an attack roll, the character's THAC0 must be known. This depends on the group and level, if the attacker is a player character or NPC, or the Hit Dice if the attacker is a monster or an animal. All 1st-level characters have THAC0s of 20, regardless of class.
For a character of level 1 through level 20, consult Table 53. This table lists the THAC0 number of each group through 20th level, so players don't have to perform any calculations.
For a character higher than 20th level, find the Improvement Rate for the character's group in Table 54. There you'll find the number of levels a character must advance to reduce his THAC0 by 1 (or more) points. Calculate the character's THAC0 according to his level.
The DMG contains the information on monster THAC0s.
Copyright 1999 TSR Inc.
Table 53 is the infamous table of groups with 20 different numbers.
So that consistent method must have been found. Condense all the attack matrices for the 4 groups, into a single line per group and call it THAC0, and then apply modifiers.
It saves space in the book, does the exact same thing. And makes for looking in the book when fighting to be unneeded since each player can have his own table on the sheet with wimple math.
To-Hit Armor Class 0.
Since zero is the mid-point of the armor classes, you just need to follow the formula when you level to get your new THACo, and the DM can always know what it takes for you to hit with a quick look rather than needing to look at the tables as well.
Bob the fighter is level 12.
That means his sheet says THAC0: 9
Bob doesn't know the monsters AC since it is his first time playing, and the bugbear he is fighting is known by the DM to have an AC 9.
9-9 = 0 Bob's player must roll in order to hit the bugbear.
REAL simple. Bob's player needs to roll a 1 (2 if using some 1=autofail).
THAC0-AC=number needed to hit.
Bob's player doesn't even have to worry about it, since he doesn't have the monster AC. So why should he bother? What if the DM created a monster NOT in the book?
He can just make up the AC for it!
Having to NOT look up one of the attack matrix tables each time a PC, NPC, monster made an attack sped up the game by leaps and bounds.
The math is simple. THAC0 just gave you all the attack rolls for a PC type in a single line, and you only needed the one number to figure out what you could hit.
As above, the THAC0 of 9 means hitting an AC 0 monster (pretty damn good AC since nekked you are AC 10) takes a roll of 9 to hit. Weaker armor by one would be AC 1. (look up stuff on Dave to find out why...) Hitting weaker armor takes a lower roll, so 8 to hit AC 1.
THAC0-AC=to hit
9-1=8
Yup still works.
Hitting AC -1 which is stronger armor than AC 0....
THAC0-AC=to hit
9-(-1)= (two minus signs equal a plus sign my second grade teacher told me so...)
9+1=10
So you can build the line all the way across the 21 armor classes.
The DM only needs to compare your roll (adjusted with modifiers), to the adjusted AC of the monsters. Or the monsters attack roll, to the adjusted AC of YOU.
All AC's are already written down adjusted. So you just pull that number off the sheet, for flat-footed, with shield, no shield, etc. Monster ACs already include any bonus magic items IF they have them.
So the logic is a simple formula rather than 4 tables to have to look up all the time and flip back and forth in the DMG for.
If THAC0 was so bad, then why did they keep it for 3rd, but just stand AC on its head, and add 10 to all the THAC0's or something like that?
BAB just moves the formula around so you don't have to worry about converting two minus signs to a plus sign. Which for even the dumbest people I know is no big mental feat. And I mean dumbest by people that couldn't find this forum without a link to click on because they don't understand how to type in
www.tgdmb.com and press the enter key.
THAC0's purpose is so you do not have to rewrite 2nd edition to conform to 3rd edition system.
It wasn't broken. It worked for everyone, but somehow people only started bitching about it when 3rd came out. Kind of like how people didn't have a problem with many things in 3rd until 4th came out and WotC said "3rd sucks!" and people decided to follow WotC and jump on their bandwagon.
WotC started the "THAC0 sucks" campaign, unless it came up in a Dragon under Paizo publishing that I don't have.
So what is the problem people really have with it? TOZ, never used it and didn't like it based on hearsay. Maybe others are the same way since the WotC campaign in order to promote 3rd edition to sell their new product? Because I NEVER heard a complaint about THAC0 prior to 3rd edition coming out. The ones I do here it from saying they don't like THAC0 are mostly people that never played prior to 3rd.
Something fishy there, is what I say, and why I am "defending" it.
There are hundreds of ways to use THAC0 to make an attack roll using the THAC0 system. You just have to pick a way and use that formula. One of those ways is the 3rd edition BAB system. It is just THAC0 standing on its head.
4th edition.
So pathetic of WotC.