OSR OSR, Ascending AC or no?

[WayOfTheFourElements]

It depends.

1. If each AC is connected to a distinct armor type (AC 7 is always leather armor or fur, AC 5 is always chain mail or scales, AC 3 is always plate mail or shells/etc.), I prefer descending AC. (For those interested, see Isle of the Unknown by Geoffrey McKinney)

2. If AC is just a number that abstractly describes how hard someone/something is to "hit", I prefer ascending AC.

 

[Charlaquin]

I’m not an OSR gal and I haven’t played any pre-3e editions of D&D (and accordingly, didn’t vote in the poll), but I will say this for THAC0: if you tell the players their target’s AC (I know, probably not something most OSR DMs are wont to do), it allows them to do the math first and figure out what number they need to roll to hit. This changes the process of rolling to hit from:

1. Roll the d20
2. Add your to-hit bonus to the result
3. Compare the result to the target’s AC to find out if you hit

to

1. Compare your THAC0 to the target’s AC to find out what number you need to roll on the d20 to hit
2. Roll the d20 to see if you hit

The latter makes for a (subtly) more psychologically satisfying experience of rolling to hit, due to having a more traditional engagement curve. By removing the extra step of calculating the total on your to-hit roll, the process of rolling becomes the climax of the attack roll, with the hit or miss being the denouement, as opposed to having the process interrupted by adding your to-hit bonus.

That said, addition is the easier than subtraction, and ascending AC is more intuitive than descending AC (because our brains tend to assume that higher numbers are better.) For these reasons, in my ideal version of D&D, AC (and DCs) would ascend with difficulty, the DM would be obligated to tell the player their target number (be it a monster’s AC or a task’s DC), and modifiers would lower the target number rather than adding to the result of the d20 roll.

In short, when you described an action, the DM would tell you what number you needed to roll to succeed, you would reduce that number by your modifier (or increase it if you had a “penalty”), and roll to see if you meet or exceed the target.

 

[UngeheuerLich]

I liked THAC0 back then. Approaching AC 0 was something that felt good.
But since we didn't use Tables and instead always calculated in our head (Roll, add bonuses, then add enemy AC) , ascending AC made it easier for the DM since players could do their math themselves easier.

The only thing, because of the slightly more complicated calculation, enemy AC was not as easily deducted.

 

[Retreater]

I've played several OSR games recently using descending AC (and started that way myself in AD&D). Personally, the only reasons I can see to use it are a) nostalgia and/or b) a GM wanting to avoid the work to convert an old adventure and putting the effort on their players.
If you're playing a character with an ability score bonus or a magic weapon, you're already adding to a d20 roll. Why add an extra step to compute what you've done?
How such a convoluted system originated in the first place is a mystery to me.

 

[The Crimson Binome]

Given preference, I'll go with ascending AC, but either way is fine.

All I ask is that you pick one and stick to it. The worst possible choice is to not pick a side, and instead write every single AC in the book using some bizarre hybrid format.

 

[Horwath]

Let's just say that THAC0 was maybe a good idea when it came out, as they didn't have any other.
And when they decided to put ascending AC and ascending attack bonus, we can now have 20/20 hindsight and say that THAC0 was one of the dumbest ideas ever.

 

[Zardnaar]

I've played several OSR games recently using descending AC (and started that way myself in AD&D). Personally, the only reasons I can see to use it are a) nostalgia and/or b) a GM wanting to avoid the work to convert an old adventure and putting the effort on their players.
If you're playing a character with an ability score bonus or a magic weapon, you're already adding to a d20 roll. Why add an extra step to compute what you've done?
How such a convoluted system originated in the first place is a mystery to me.

I think it had something to do with naval class rating the ships.

 

[ccs]

Let's just say that THAC0 was maybe a good idea when it came out, as they didn't have any other.
And when they decided to put ascending AC and ascending attack bonus, we can now have 20/20 hindsight and say that THAC0 was one of the dumbest ideas ever.

Hardly one of the dumbest ideas ever (not even in D&D). It was just an artifact of the games miniature wargaming origins. Descending wasn't even the only option in the beginning, just likely that no one in OD&D-1e days even thought to flip it to ascending. Because the creators were building off what they were already used to & the rest of us just took the rules at face value & got on with the game.
2e was specifically made to be backwards compatible so descending was intentionally kept. Though if they'd just kept the "To Hit" charts & not tried to be all slick & using the THAC0 acronym 30 years of commentary could've been avoided.....
3e? Flipping the AC chart to ascending wasn't exactly a stroke of genius.

 

[commandercrud]

Game mechanics don't make a game OSR or not. Descending AC makes perfect sense and the only flaw is how bad people are at basic math.

 

[Lanefan]

Descending AC yes.

THAC0 no.

They are not the same - one can nicely have and use descending AC while never once touching a THAC0 table or mechanic. For me THAC0 just adds an extra and unneeded step to the arithmetic.