Solomoriah Speaks E20: THAC0

In this video I address some misconceptions about THAC0 in classic D&D games, admit some embarrassing things about myself, and explain why I chose ascending AC for Basic Fantasy RPG despite using literally no other "modern" mechanics in the game.

[@chameleondream]

Good one Chris, and for the record you're not alone. I once was experimenting with a system where basically instead of rolling a d20 and adding modifiers to it, you started with a standard 3 to 18 score and rolled a d20 and a d6. If the d20 turned up even you added the d6 to the score. If odd you subtracted it. What did I discover? I hate subtraction. Rolling one of those odd numbers felt like getting a little electric shock, or like lighting up the nose on the patient in a game of Operation, so I scrapped it. I don't think it's a matter of complexity or mental load. I think we humans just have primal negative reaction to subtraction. It's what remains of our ape brain thinking that it's better to grab the banana than have the banana grabbed from you. And that's what's wrong with THAC0. It's not that we can't do it. We just don't want to.

[@Eron_the_Relentless]

I agree on all points. Most descending Armor Class (hereafter AC) adherents nowadays argue from a position that all they knew was ascending Armor Class (hereafter AAC) before coming to the OSR, so they identify AC as "old school" and argue in favor of it for that reason and that reason alone. Us old timers had to play for decades with AC, often not even having the foresight to employ the shortcut I'm about to explain. While it doesn't improve the intuitiveness of the mechanic, ease of use is made functionally equivalent to AAC by changing around how the numbers influence the die roll, and what target number to hit. Classically, the THAC0 attack equation was "if THAC0 - (die roll + mods) = THAC0, then attack hits" They both stand against the AAC equation "if die roll + mods >= enemy AAC, then attack hits" There is still a chance of subtraction in the second equation (and a greater chance at higher levels), but it doesn't take a genius to see that the second equation is much simpler than the first from a maths perspective. The argument in favor of the former over AAC (the third equation) is preposterous at onset. Willfully obstinate. Nostalgic puffery. Nonsense. It's an argument often made from a place of willful nostalgia (old timers) or privilege in having grown in the environment of AAC (young 'uns) and are willfully rebelling against it. Nothing more, and frankly not worth taking seriously. Now, if arguing from an Attack Matrices perspective technically the process is functionally identical for AC and AAC, the only problem would be finding some game to have actually put AAC on an attack matrix instead of just using the simple equation AAC was built for. Those who prefer a table look up to any maths at all have a point in aiming at AC over AAC because, to put it simply, the tables don't exist.

[@praxistallyogarro]

Thanks for the new video Mr.Gonnerman.

[@bankuei]

I really appreciate you speaking about the issues of cognitive load. I think a lot more RPG game designers should take it into account, not just "crunch" but for many things; most of the lighter games end up shunting a lot of work on to the GM, just in an unstructured fashion, which is also a cognitive load, just a different one. As a kid I had to teach myself from the books and DM for others, I hated both the charts and THACO, and it wasn't until I was out of college, in the mid 2000s someone came up with "Roll d20 + target's descending AC to meet or beat 20" and that was MUCH easier for me to work with, however, at that point we had already moved on to ascending AC (and, for me, other RPGs in general).

[@ChrisGonnerman]

The "cost" of running a game is rarely considered, I've noticed. Saying that a procedure is "easy" is often an excuse to add more "easy" procedures, and shortly the game becomes unmanageable for me.

[@DustinianCamburides]

A good friend of mine refers to "Descending AC" as "Condescending AC" because of the tone of some (not all) THAC0 apologists.

[@ChrisGonnerman]

Sounds about right...

[@davidcauley9400]

Good stuff Chris.

[@ChrisGonnerman]

Thanks!

[@namelessjedi2242]

I’m in the same boat as you. I’ve had trouble with descending since I started playing in the 80’s. I can use it, but ascending is greatly preferred.

[@jjjumpercables8513]

It's interesting how everyone's brain works slightly different. I also have always had trouble quickly doing math in my head, and it's why I actually prefer THAC0. At least in my experience, you're always doing arithmetic with smaller numbers using THAC0, especially as you go up in levels and both the PC and monster/NPC ACs get better (lower). It's always quicker for me to add/subtract 1-4 from my THAC0 value than add +13 to my d20 roll like when we play 5E.

[@doctorxombie]

Thanx for sharing your thoughts and challenges as a GM. Makes me feel not so alone trying to figure out the best ways that work for me personally running a game. Always looking forward to more videos from you. 😁

[@ChrisGonnerman]

Glad I could help!

[@sinemi3]

Definitely reaction rolls is one of the things newer editions are lacking. Excellent video!

[@shirleynace1314]

I love Basic Fantasy because it “feels right”. Yes!

[@ChrisGonnerman]

Thank you! Glad you like it!

[@DMTalesTTRPG]

There was a push to use Ascending AC in 2e but TSR was afraid it was too much of a change.

[@ChrisGonnerman]

Guess I was out of it by then.

[@DMTalesTTRPG]

@@ChrisGonnerman I only found this out after rejoining the hobby in 2020!

[@jocool4606]

Love this. Do what works for your game and table! It is all arbitrary. Also love the guest appearance by Coal.

[@ChrisGonnerman]

He's a good boy.

[@retrodmray]

Thnx for the vid, Chris. As a really old school DM from the 1E era, having then ran 2E from the minute it hit the shelves until 2003, the 1E To-Hit charts did allow for PC's to not encounter unhittable enemies and monsters. But, if I remember correctly, using those tables also required you to be using the To-Hit Adjustments of Weapons-vs-AC. Might be wrong on that though... don't have my book with me. When we switched to THACO in 2E, we also added that a 20 always hit, to both not allow unhittable enemies/monsters and to also keep Weapons-vs-AC Adjustments out of it....cumbersome look-ups always ensued. But, it was a bit problematic when you, as DM, set up some cool stuff with your Big Bad, and 20's around the table eliminate that. He-He 😅 Anyway, thnx again for this.... and yes, it only matters as to what works for you. 🤓👍

[@RHampton]

Fletcher Pratt's naval wargame (1943) is allegedly the origin of hit points. Armor was rated in thickness of the steel on the ships in inches. I am looking at the chart and it is 1" to 18" You had to cross reference the range at which the shell was thrown and the caliber of the gun to see if penetration occurred on a hit.

[@darjr]

Oh! I was at the Lage Geneva Museum run by the city when I was shown Gary’s copy of chainmail that had his notes in the back that first converted to d20.

[@Joshuazx]

If I thought of ascending AC myself, I would have used it over descending AC / Thac0 too.

[@Adamthegeek70]

I am glad BFRPG has what it has, it is why I like it. I can do math in my head. Or rather I could, I am 53 and I am getting dumber I think LOL. But looking stuff up on a table was always slow for me LOL.

[@darjr]

I love that you made the choice you did.

[@ChrisGonnerman]

Thanks!

[@rdmsh]

OSE has both as well

[@Penfold497]

Happy thanksgiving Chris Will you ever talk about omitting the assassin

[@ChrisGonnerman]

Didn't know it was an issue. Also, did not "omit" the assassin; BFRPG is based on the 1981 game which had only four classes. And we have an Assassin subclass document on the Downloads page.

[@Penfold497]

@@ChrisGonnermanthanks Chris, that answers my question.

[@robbabcock_]

It doesn't much matter if you use ascending or descending, THAC0 or a table. They're not even mutually exclusive; everyone I know that uses THAC0 has the chart filled out for all the values from -10 to +10. Too much is made of the chosen mechanic as people forget the rules are a means to an end, not the end goal itself.

[@GolshanIbnys]

8:30 This is what I do for 1e. They have their part of the matrix on their character sheet and I ask them to not tell me what number they roll but what AC they hit.

[@johnwhite2412]

Exactly!!! We used tables. Not THAC0.

[@rdmsh]

Funny how AAC seems so obvious in hindsight. I played a lot of 2e and have a fondness for thaco but would use if for new players

[@DMTalesTTRPG]

Rant all you want!

[@ChrisGonnerman]

Thanks, I will!

[@BScalise97]

This’ll be juicy!

[@ChrisGonnerman]

Thanks Brian!