How is Stealth supposed to work in AD&D/Basic?

[Yora]

Both in AD&D and Basic, the chance a thief has to Hide in Shadows is a meager 10%. In any other game, a 90% chance to fail at a stealth check would mean "you'd have to be insane to try". I wouldn't even try to sneak up on someone unless I think I have at least 80% chance to do it.

But I don't think that is how the rules were meant to work. After all, the skills are called Move Silently and not "sneak" and Hide in Shadows and not "hide". My personal assumption would be that these skills are meant to represent superhuman sneaking and hiding. When it says "Move Silently", you really are moving perfectly silent. Even in a completely quiet room with a guard listening for anyone nearby, you will not be heard if you make the roll. When you hide in shadows, you don't just hide, people won't notice you even though they are staring right at you from a close distance.

Under such an interpretation it makes sense that for first level thieves the chances are so low. The thief wants to sneak past a guard, but the GM decides that the guard would hear this. But the player does not know and just gambles that the guard is distracted enough and there is enough noise, so that anyone can sneak past him. However, before the GM says "the guard hears you and turn around", he first makes a Move Silently roll. And with a 15% chance, the thief might still be undetected, even though anyone else would have been heard.

That's an interpretation that would make sense to me. But I've never actually seen anything written in the books that would support that. Is there any explaination in AD&D or Basic how stealth is supposed to work for thieves and also other characters?

[LibraryOgre]

The way I have always done it is that, if you are successful, then surprise is automatic. If you fail, or don't have the abilities, then you fall back on the regular surprise rules.

[Jay R]

When we played it, either moving silently or hiding in shadows was a desperation move for a Thief, unless there was some distraction, often provided by the rest of the party.

[LibraryOgre]

When we played it, either moving silently or hiding in shadows was a desperation move for a Thief, unless there was some distraction, often provided by the rest of the party.

In 2e, thieves tended to specialize... either as Box Men (FART & OL) or Sneaks (HS & MS). You could pretty quickly get decent scores that way.

[Jay R]

In 2e, thieves tended to specialize... either as Box Men (FART & OL) or Sneaks (HS & MS). You could pretty quickly get decent scores that way.

True. In my last 2E game, I had to explain more than once that, yes, I was a Thief, and no, I wasn't stealing anything. I also had to remind the DM more than once that he wasn't refusing to steal because he was Lawful, but because traveling with a Paladin was the most lucrative thing he'd ever done, and he wasn't willing to risk losing it.

[aspekt]

True. In my last 2E game, I had to explain more than once that, yes, I was a Thief, and no, I wasn't stealing anything. I also had to remind the DM more than once that he wasn't refusing to steal because he was Lawful, but because traveling with a Paladin was the most lucrative thing he'd ever done, and he wasn't willing to risk losing it.

And thus the more appropriate naming in 3.x of Rogue.

[Thrudd]

Both in AD&D and Basic, the chance a thief has to Hide in Shadows is a meager 10%. In any other game, a 90% chance to fail at a stealth check would mean "you'd have to be insane to try". I wouldn't even try to sneak up on someone unless I think I have at least 80% chance to do it.

But I don't think that is how the rules were meant to work. After all, the skills are called Move Silently and not "sneak" and Hide in Shadows and not "hide". My personal assumption would be that these skills are meant to represent superhuman sneaking and hiding. When it says "Move Silently", you really are moving perfectly silent. Even in a completely quiet room with a guard listening for anyone nearby, you will not be heard if you make the roll. When you hide in shadows, you don't just hide, people won't notice you even though they are staring right at you from a close distance.

Under such an interpretation it makes sense that for first level thieves the chances are so low. The thief wants to sneak past a guard, but the GM decides that the guard would hear this. But the player does not know and just gambles that the guard is distracted enough and there is enough noise, so that anyone can sneak past him. However, before the GM says "the guard hears you and turn around", he first makes a Move Silently roll. And with a 15% chance, the thief might still be undetected, even though anyone else would have been heard.

That's an interpretation that would make sense to me. But I've never actually seen anything written in the books that would support that. Is there any explaination in AD&D or Basic how stealth is supposed to work for thieves and also other characters?

There weren't really any rules for individual active stealth, other than the thief. Surprise rolls represent both the stealth and perception roll in one.
In 1e AD&D, the ranger had a reduced chance of being surprised, representing increased awareness, and some monsters have increased chance to surprise due to stealthiness.

So, taking those examples into account, the DM could allow modifications to surprise rolls based on the party's actions, or even deciding that their actions warrant automatic surprise or no chance of being surprised.

The difference with 3e here is that the party gets one roll representing them collectively. Individuals might have modifiers that apply only to them, like high dex reducing the effect of surprise, or Rangers not being surprised when the rest of the party might be. A thief can go it alone and override any chance of detection with use of their skills, like you said. If they succeed at their roll at the beginning of the turn, they could walk past a monster and no surprise roll happens at all, there is no encounter unless they initiate it (or the creature has enhanced senses).