A better THAC0?

vivsavage · Apr 27, 2017

To make an attack in 2e AD&D, you subtract the enemy's AC from your THAC0 score before rolling. So if your THAC0 is 15 and the enemy's AC is -1, you subtract -1 from 15, meaning you need a 16+ to hit. While it works fine, many people find the system unintuitive since you are really adding the inverse of the AC to your THAC0.

Why not simply use the defender's AC as a modifier to the dice roll itself? No need to recalculate your THAC0 that way, and you don't use any inverse values, so to speak. Mathematically it's the same result, but sees to me to be more intuitive. If the DM doesn't want to reveal the enemy's AC, the player can simply roll the dice and compare it to his THAC0, giving a number indicating what AC has been hit. For example, if the player with the 15 THAC0 rolls a 17, he announces he has hit AC 2 or better.

Yes? No? Maybe?

Nagol · Apr 27, 2017

That's pretty much how it runs at my tables and the table I sat at for 1e (pre-THAC0) and 2e. Player rolls, announces effective AC hit and then DM resolves. THAC0 was adopted to simplify the notation (by limiting the need for to-hit tables by level) more than the math I think. Pre-THAC0 we used THAC10 -- everyone's sheet had the to-hit number for AC 10 on it and the roll hit AC (10 - dice overage).

JonnyP71 · Apr 27, 2017

I keep a list of the PC's THACOs. When they roll to hit I tell them any situational modifiers they may have, and they tell me the total. I then tell them if they have hit or not. I can usually tell them that without having to refer to my list.

It doesn't matter one iota whether they understand THAC0 or not. I grew up with Basic and Advanced D&D so it is second nature to me. My current 1E group are all new to the system and some of them are starting to grasp it, but whether or not they have has no real bearing on the game itself.

In fact, I find RPGs to be more fun when the players don't have an in-depth knowledge of the mechanics.

(and will people please stop saying 1E was pre THAC0, or that THAC0 was introduced in 2E!!!! Every monster had a 'to hit armour class 0' listed in the 1E DMG, and the actual abbreviation THAC0 was 1st used in the UK series of modules in 1983!!!!!)

vivsavage · Apr 27, 2017

JonnyP71 said:
(and will people please stop saying 1E was pre THAC0, or that THAC0 was introduced in 2E!!!! Every monster had a 'to hit armour class 0' listed in the 1E DMG, and the actual abbreviation THAC0 was 1st used in the UK series of modules in 1983!!!!!)

I'm not sure who is saying that. The term THAC0 is just more associated with 2e, but I don't think anyone is saying 2e invented the concept.

Nagol · Apr 27, 2017

vivsavage said:
I'm not sure who is saying that. The term THAC0 is just more associated with 2e, but I don't think anyone is saying 2e invented the concept.

IIRC I first saw THAC0 in a Judges' Guild product during 1e.

Nagol · Apr 27, 2017

JonnyP71 said:
I keep a list of the PC's THACOs. When they roll to hit I tell them any situational modifiers they may have, and they tell me the total. I then tell them if they have hit or not. I can usually tell them that without having to refer to my list.

It doesn't matter one iota whether they understand THAC0 or not. I grew up with Basic and Advanced D&D so it is second nature to me. My current 1E group are all new to the system and some of them are starting to grasp it, but whether or not they have has no real bearing on the game itself.

In fact, I find RPGs to be more fun when the players don't have an in-depth knowledge of the mechanics.

(and will people please stop saying 1E was pre THAC0, or that THAC0 was introduced in 2E!!!! Every monster had a 'to hit armour class 0' listed in the 1E DMG, and the actual abbreviation THAC0 was 1st used in the UK series of modules in 1983!!!!!)

The DMG mention is disingenuous. The 1e DMG has tables cross-referencing class levels (or hit dice for monsters) with target AC. The intersections contain the to-hit number. Target AC runs from -10 to 10 though there are rules in the sidebar for extending the range as necessary. AC 0 is not called out or published separately.

IIRC, I first saw THAC0 in a Judge's Guild product along with HTK (Hits to Kill -- their version of hit points to avoid trade dress issues).

THAC0 or something like it is more helpful on products on the DM side since it reduces the number of table lookups during combat.

GMMichael · Apr 27, 2017

vivsavage said:
Why not simply use the defender's AC as a modifier to the dice roll itself? No need to recalculate your THAC0 that way, and you don't use any inverse values, so to speak. Mathematically it's the same result, but sees to me to be more intuitive. If the DM doesn't want to reveal the enemy's AC, the player can simply roll the dice and compare it to his THAC0, giving a number indicating what AC has been hit. For example, if the player with the 15 THAC0 rolls a 17, he announces he has hit AC 2 or better.

Yes? No? Maybe?

Yes. And I have the better name for you, too:

THWACZ

Stand for To Hit (enemies) With Armor Class Zero. Has a little thug-tone to it: "what's your THWACZ, bro?"

ccs · Apr 27, 2017

Nagol said:
The DMG mention is disingenuous. The 1e DMG has tables cross-referencing class levels (or hit dice for monsters) with target AC. The intersections contain the to-hit number. Target AC runs from -10 to 10 though there are rules in the sidebar for extending the range as necessary. AC 0 is not called out or published separately.

This is true. But if you just look back on P.196-P.215, 3rd column, you'll see that "To Hit A.C. 0" is indeed in the 1e DMG.

ccs · Apr 27, 2017

vivsavage said:
To make an attack in 2e AD&D, you subtract the enemy's AC from your THAC0 score before rolling. So if your THAC0 is 15 and the enemy's AC is -1, you subtract -1 from 15, meaning you need a 16+ to hit. While it works fine, many people find the system unintuitive since you are really adding the inverse of the AC to your THAC0.

Why not simply use the defender's AC as a modifier to the dice roll itself? No need to recalculate your THAC0 that way, and you don't use any inverse values, so to speak. Mathematically it's the same result, but sees to me to be more intuitive. If the DM doesn't want to reveal the enemy's AC, the player can simply roll the dice and compare it to his THAC0, giving a number indicating what AC has been hit. For example, if the player with the 15 THAC0 rolls a 17, he announces he has hit AC 2 or better.

Yes? No? Maybe?

Sure. You could do that.

OR....

You could just write out the entire chart ONCE per class. Left hand column = class lv 1-20, grouped by where the # improves. Top line = ACs from 10 - -10.
Fill in all the #s.
Takes about 5 minutes. (including loading the paper into the printer)

Roll dice, apply modifiers, look at chart, tell DM the result. This system has been working for 43 years, it'll keep working till the end of time.

ccs · Apr 27, 2017

JonnyP71 said:
In fact, I find RPGs to be more fun when the players don't have an in-depth knowledge of the mechanics.

We're not talking about intricate/arcane/obtuse, mechanics here (like say the 3x grappling rules

), just basic math....
Basic math & reading = two skills that unless you're a small child you should possess in order to be allowed to play this game.