D&D General Mechanical differences between AD&D and Basic?

[Malmuria]

AD&D: where no matter how many times you read the rules you still might miss the part where helmets give you increased AC vs randomly determined head attacks, varying by intelligence of the attackers, but restricts vision to 60 degrees.

 

[Lyxen]

Compatible enough that an adventure* written for either Basic or 1e can easily be run in the other system with next-to-no conversion required: they're almost completely interchangeable.

* - the only real exceptions I can think of are the M and I level adventures for BECMI, but they're bad enough in general anyway that if you're thinking of running one my advice would be don't.

Exactly, just pick the monster from 5e instead of the one from the original module and you can usually run it straight out of the box.

* I liked Into the Maelstrom because of the huge fleets and naval battles, and the "Odyssey" feel of it.

 

[jeffh]

Well I'll be dipped.

That's kind of dumb though, the head is a lot smaller of a target and almost everyone will try to protect it with their weapon or shield or if all else fails by leaning back. Even letting an arm get cut off is better than taking a solid headshot without a helmet in realistic combat, not that any version of D&D has really tried to be that. There should be some kind of penalty for lacking head protection, if you're interested in being that simulationist, but hitting the head shouldn't be against the same AC as hitting an entire unarmoured person.

 

[Lyxen]

AD&D: where no matter how many times you read the rules you still might miss the part where helmets give you increased AC vs randomly determined head attacks, varying by intelligence of the attackers, but restricts vision to 60 degrees.

AD&D is full of inconsistent rules like this, and that one is really bizarre, because you could be wearing a helmet without armor and get a great AC for the head, but you also might be in magical armor and have AC -5 and your head would still be AC 1 with a helmet.

It is assumed that an appropriate type of head armoring will be added to the suit of armor in order to allow uniform protection of the wearer. Wearing of a “great helm” adds the appropriate weight and restricts vision to the front 60° only, but it gives the head AC 1. If a helmet is not worn, 1 blow in 6 will strike at the AC 10 head, unless the opponent is intelligent, in which case 1 blow in 2 will be aimed at the AC 10 head (d6, 1-3 = head blow).

When you couple this with the incredibly complex "weapon vs. AC" which explains what types of weapons are best against what type of armor, you have a very complex system, and most tables did not play that.

 

[Mannahnin]

The helmet rules seem like a situational thing Gary came up with at some point to "realistically" simulate why helmets are important (and thus, for example, why removing your helmet to listen at a door is risky even without earseekers!), but probably didn't play with.

Rather like the weapon vs. AC charts, which he threw in initially as a way to appeal to more simulationist wargamers (the modifiers are basically a conversion of the charts from Chainmail) but later said he never used himself. Which makes sense; because they screwed up the math in them but those charts were never officially corrected as far as I can recall.

 

[Lyxen]

The helmet rules seem like a situational thing Gary came up with at some point to "realistically" simulate why helmets are important (and thus, for example, why removing your helmet to listen at a door is risky even without earseekers!), but probably didn't play with.

Rather like the weapon vs. AC charts, which he threw in initially as a way to appeal to more simulationist wargamers (the modifiers are basically a conversion of the charts from Chainmail) but later said he never used himself. Which makes sense; because they screwed up the math in them but those charts were never officially corrected as far as I can recall.

Exactly, these were more like a collection of options that you could use to get the game more or less simulationist, not rules that I've mostly seen in play.

 

[Malmuria]

The helmet rules seem like a situational thing Gary came up with at some point to "realistically" simulate why helmets are important (and thus, for example, why removing your helmet to listen at a door is risky even without earseekers!), but probably didn't play with.

Rather like the weapon vs. AC charts, which he threw in initially as a way to appeal to more simulationist wargamers (the modifiers are basically a conversion of the charts from Chainmail) but later said he never used himself. Which makes sense; because they screwed up the math in them but those charts were never officially corrected as far as I can recall.

A lot of these simulationist aspects of AD&D contrast starkly with the appeal of basic for OSR-style games. The play style of AD&D is OSR (high lethality, open world, no pre-determined plot) but the main reason you wouldn't look to your character sheet for answers is that the AD&D sheet is byzantine and maximalist and probably was never completely filled out to begin with. The OSR trends towards simplicity, light rule sets, rulings not rules, and the emergent play that results is probably weighed down by a lot of the finicky rules. As I remember, the main draw of AD&D as a youth was, well for one it had the word "advanced" in it, and you could separate race and class, and I could buy and use the psionic handbook.

Also: the purpose of the 1e DMG is in large part to provide these overly detailed subsystems, along with Gygax's editorialism. This leaves a confusing legacy for 5e, which requires neither of those things, leading to a dmg that provides vague and insipid advice interspersed among somewhat useful random tables

 

[steeldragons]

Uhmmm...ok...Let's see what I can throw together off the top of my head (several of these are probably already in other posts, I would imagine)

Well, you mentioned the first big/noticeable one: Race as Class.
From there we go to Race AND Class...

Races in B/X-BECMI: Human, Elf, Dwarf, Halfling. Done.
Races in AD&D: Human, Elf (assumed High), Dwarf (Hill or Mountain), Halfling (Hairfoot, Stout or Tallfellow), Half-elf, Half-orc, Gnome. AND, with 1e's Unearthed Arcana, almost all non-humans get 1-5 subraces that became playable options.

Classes in Basic: Fighter, Magic-User, Cleric, Thief (available to Humans only!), Elf (Ftr/MU, basically) as class, Dwarf (Ftr) as class, Halfling (Ftr/Thf, basically) as class.
Classes in AD&D: Fighter, Magic-User, Cleric, Thief, Paladin, Ranger, Druid, Illusionist, Assassin, Monk...arguably, in appendices, Bard and Psionicist. Cavalier, Barbarian, and Acrobat added in 1e's Unearthed Arcana.

ALIGNMENT! In Basic: Lawful, Neutral, Chaotic.
In AD&D an Ethos axis (Lawful, Neutral, Chaotic) and a Mores axis (Good, Neutral, Evil) and, thus, the Nine combinations of Alignment.

Multiclassing in Basic: nonexistent.
Multiclassing in AD&D: available to non-human options in completely independent combinations, e.g. Dwarves couldn't be the same classes or class combo's as Half-orcs who couldn't be the same classes/combos as Elves, etc... Humans were allowed "Dual classing" but not multiclassing.

Equipment: AD&D had exponentially more options for armors and weapons than B/X/ECMI.

In AD&D Casting times for spells and Weapon Speeds were a thing for combat, not that we necessarily used them religiously (or at all, from game to game). Not so in Basic.

I feel like there were other "in combat" round by round kind of differences, but not really remembering what they were. Initiative was basically the same, I think...There was "Side vs. Side" combat tracking versus individual, but that was Basic and AD&D. Changed to the individual initiative we know today in later editions.

Spell lists in AD&D were significantly more beefed up than in Basic. Especially after 1eUA.
Treasure and Magic Item lists were significantly more beefed up in AD&D than Basic. AD&D had Artifacts/Relics. You really didn't get to/see "Artifact" level items in Basic until/unless you got to the "Companion" (i.e. "C") set of BECMI. B/X didn't have them at all.

AD&D had a chart for EVVVVerything. There was a %die for just about anything you needed. Basic used percentile dice much less, though both used them for Thieves Skills.

Think that's about it that i can come up with without pulling out books... So, yeah, there were some significant differences but the general playing of the game - ability scores, saving throws, how to roll attacks and damage (even if the damage die was different), and so on - was mostly the same/easily transferable.

 

[overgeeked]

Reading back over the AD&D books after years away and I’m struck by how much closer we played to B/X despite using the AD&D books. The example that jumped out at me today: the light spell. Turns out we were doing it wrong for decades. We always used the B/X version that allowed blinding a target.

If you want the best of both, check out Old-School Essentials. Their Basic Fantasy line is built on B/X (as exact a copy as they can make) but they have recently put out Advanced Fantasy books which present AD&D stuff for the B/X rules. So you can have the race/class split of AD&D, use their conversions of the AD&D classes, along with other bits and bobs and run it all with B/X.

 

[tetrasodium]

How compatible are we talking about here?

Your character would use a given table based on their race/class as appropriate & there were probably some differences but converting between or running something in the other was pretty much a triviality. There were some minor mechanical differences but they were not a big deal. 3.0 3.5 & PF were similar spreads as basic/ad&d