What is wrong with THAC0?

shadzar · Post by **shadzar** » Sat Oct 31, 2009 7:52 am

I forgot how to search titles only in this version of phpBB, so if a thread exists on this topic, merge it or something if that hack is installed.

What is the real problem people have with THAC0?

I have never got a straight answer besides, "it doesn't make sense". What doesn't make sense about it? What is the REAL problem people have/had with THAC0?

Username17 · Post by **Username17** » Sat Oct 31, 2009 8:39 am

The problem is that a +1 bonus is a bonus to a hidden number that is subtracted from your to-hit number. When you get a +1 bonus to-hit, it doesn't actually add to a named quantity, it simply increases the number of numbers on the d20 where you would hit. But since there's no name for that quantity, the entire system is unnecessarily obtuse.

-Username17

shadzar · Post by **shadzar** » Sat Oct 31, 2009 10:27 am

Huh? You add the +1 to your to-hit dice roll, just as in 3rd.

Murtak · Post by **Murtak** » Sat Oct 31, 2009 10:40 am

THAC0: To determine whether I hit an AC of -5 I have to take my THAC0, subtract the AC, then check whether I rolled above that number. Oh, and of course attribute checks, skill checks and rogue skill checks all have different mechanics.

3rd: I roll a d20 and add my static to-hit bonus. If it is at least as high as the target's AC, I hit it. Everything else works the same way.

3rd does not require you to compute a new to-hit number for every opponent, it does not require fiddling around with negative numbers, and it works the way the rest of the system does.

Username17 · Post by **Username17** » Sat Oct 31, 2009 10:46 am

shadzar wrote:Huh? You add the +1 to your to-hit dice roll, just as in 3rd.

If you think that's how it works, then that is the reason why Thac0 is a shitty system that they got rid of. Hint: that's not how it works.

-Username17

shadzar · Post by **shadzar** » Sat Oct 31, 2009 12:05 pm

You add bonuses/penalties to your die roll.

THAC0 15
AC 5
+1 sword
Dice roll 9

Congrats a hit!

dice roll+modifiers>=THAC0-AC==hit
9+1>=15-5==true
10>=10==true

@Murtak:

Yes I often hear people bad at 2nd grade math also thinking THAC0 as being bad for forcing them to have to subtract.

Username17 · Post by **Username17** » Sat Oct 31, 2009 12:18 pm

How do you think Armor plusses work?

You have an AC of 5, because you are wearing chainmail.
But it's +1 chainmail. So your AC is 4.

What are you adding +1 to?

-Username17

Lago PARANOIA · Post by **Lago PARANOIA** » Sat Oct 31, 2009 12:21 pm

shadzar wrote:Yes I often hear people bad at 2nd grade math also thinking THAC0 as being bad for forcing them to have to subtract.

Counterargument: We should get rid of THAC0 because simpering, sexually-frustrated control freak grognards want to suck stale Cheeto-chunked pebbles from Gygax's decomposing asshole so hard, since they can give no reason why they want to keep it other than the fact that Gygax vomited that rule onto the page 30 years ago.

See how easy that was? Now it's your turn.

CatharzGodfoot · Post by **CatharzGodfoot** » Sat Oct 31, 2009 2:58 pm

Lago PARANOIA wrote:Counterargument: We should get rid of THAC0 because simpering, sexually-frustrated control freak grognards want to suck stale Cheeto-chunked pebbles from Gygax's decomposing asshole so hard, since they can give no reason why they want to keep it other than the fact that Gygax vomited that rule onto the page 30 years ago.

You really do have a way with words, Lago.

I don't like THAC0 because calculating it takes slightly longer than the 'roll, add, compare to DC' method. Sure, it's a very slight time increase, but it's something you have to do a lot.

Count Arioch the 28th · Sat Oct 31, 2009 3:04 pm

I do know that while using THac0, I always had to look at a chart, every time an attack was rolled. I know that certain people would be disdainful at my ability to not memorize multiple spreads of 20 numbers, but it's just easier to say "Roll a 14 or higher to hit".

Josh_Kablack · Post by **Josh_Kablack** » Sat Oct 31, 2009 4:07 pm

The algorithm for determining whether a die roll is a hit or miss in the THACO system includes an unnecessary "multiply by -1" step when compared to the 3.x and 4th ed systems.

The fact that it is merely third grade math which everyone here can do is in no way a valid reason to include an extra unneeded step in task resolution.

I could make a stronger argument for a rule where players had to interrupt the game and do a set of jumping jacks prior to each d20 roll - at least that would help with the health and image of gamers in general instead of merely adding complexity for the sake of complexity.

shadzar · Post by **shadzar** » Sat Oct 31, 2009 5:10 pm

FrankTrollman wrote:How do you think Armor plusses work?

You have an AC of 5, because you are wearing chainmail.
But it's +1 chainmail. So your AC is 4.

What are you adding +1 to?

-Username17

THAC0 15
AC 5 (+armor granting +1)
+1 sword
Dice roll 9

Boo you missed!

dice roll+modifiers>=THAC0-AC+AC_bonus==hit
9+1>=15-5+1==false
10>=11==false

Psychic Robot · Post by **Psychic Robot** » Sat Oct 31, 2009 5:20 pm

THAC0 15
AC 5 (+armor granting +1)
+1 sword
Dice roll 9

Boo you missed!

BAB +5.
AC 15.
+1 sword.
Dice roll 9.

Yay, you hit.

dice roll+modifiers>=THAC0-AC+AC_bonus==hit
9+1>=15-5+1==false
10>=11==false

Dice roll + modifiers >= AC = hit.

The simple fact of the matter is that subtraction is exponentially more difficult than addition at 3:00 AM, particularly in a Mountain Dew-addled state of mind.

Judging__Eagle · Post by **Judging__Eagle** » Sat Oct 31, 2009 5:20 pm

It's an extra set of steps for something that is done the most in the game.

That alone is the best reason to make it as straightforward as possible.

shadzar · Post by **shadzar** » Sat Oct 31, 2009 5:30 pm

So it is pretty much not the math, just the extra step is all the problem is?

Murtak · Post by **Murtak** » Sat Oct 31, 2009 5:31 pm

shadzar wrote:THAC0 15
AC 5 (+armor granting +1)
+1 sword
Dice roll 9

Boo you missed!

dice roll+modifiers>=THAC0-AC+AC_bonus==hit
9+1>=15-5+1==false
10>=11==false

Actually you are supposed to modify your THAC0. Thus:
9 >= (15 - 1) - (5 - 1)
9 >= 14 - 4
9 >= 10

You taking a shortcut nicely demonstrates why THAC0 is bullshit. There are easier ways to calculate a to-hit roll. Not that THAC0 is hard, but there is no need for the added complexity, however small.

Murtak · Post by **Murtak** » Sat Oct 31, 2009 5:32 pm

shadzar wrote:So it is pretty much not the math, just the extra step is all the problem is?

That and having another mechanic when you can just use the same mechanic for attack rolls, saving throws and skill checks.

shadzar · Post by **shadzar** » Sat Oct 31, 2009 5:34 pm

Skill checks? You mean IF you are using the optional skill rules?

Why should an attack roll use the same system as saving throws?

Psychic Robot · Post by **Psychic Robot** » Sat Oct 31, 2009 5:41 pm

Why should an attack roll use the same system as saving throws?

Because it's easier.

Count Arioch the 28th · Sat Oct 31, 2009 5:47 pm

shadzar wrote:Skill checks? You mean IF you are using the optional skill rules?

Why should an attack roll use the same system as saving throws?

Why would you not do that?

Username17 · Post by **Username17** » Sat Oct 31, 2009 5:47 pm

Shadzar wrote:THAC0 15
AC 5 (+armor granting +1)
+1 sword
Dice roll 9

Boo you missed!

That... doesn't even work. You failed to provide something that the +1 armor was modifying. According to your posted math, the effective AC should be 6, making the target number an 8+. That you failed to even correctly notate how the math works is why the Thac0 system is bullshit.

This discussion should now be over. It should be fucking obvious why this system is overly complicated if you failed to actually write it up correctly when trying to explain how it wasn't overly complicated.

The answer is that a +1 armor adds to an invisible quantity that is subtracted from your AC. Which means that +1 is never added to any named positive value at any point. And that's dumb.

-Username17

shadzar · Post by **shadzar** » Sat Oct 31, 2009 5:49 pm

Count_Arioch_the_28th wrote:
shadzar wrote:Skill checks? You mean IF you are using the optional skill rules?

Why should an attack roll use the same system as saving throws?
Why would you not do that?

Which?

Count Arioch the 28th · Sat Oct 31, 2009 5:50 pm

Why would you not have the same system for saving throws as you do attack rolls?

shadzar · Post by **shadzar** » Sat Oct 31, 2009 5:52 pm

Frank you might want to learn to use a number line. It will help you greatly in life. I showed exactly where it modified. Just like any other number in the game it modifies the math.

Do you mean your characters go around shouting +1 this and +4 that, and other mechanics terms that have no use to the character? That's dumb.

shadzar · Post by **shadzar** » Sat Oct 31, 2009 5:55 pm

Count_Arioch_the_28th wrote:Why would you not have the same system for saving throws as you do attack rolls?

Technically you do, but not to the extent of attacking the "save value" directly.

They all function as roll a number and add modifiers, and compare it to the target number, so they technically are all the same system; they just don't all use the same numbers.