How much game mechanics do PCs get to see?

[Terwox]

I'll usually tell my players direct AC's after a few swings, a round or two of fighting, anyone who fights a lot can sum things up quickly enough.
Just depends on the game, really, I leave a lot of stuff open, it's alright.

OTOH, I highly enjoy playing in games where I don't roll any of my own dice... I'm a number cruncher, and I'll just start running numbers through my head as soon as the dice start falling... unless I can't see them. It helps me get into the game quite a bit more, I think. Sadly, the opportunity for me to do this comes up really rarely.
I think most of my players would be VERY displeased if I tried to DM like that, though.

Most of the time I'll give DCs after the rolls, if it's an optional skill check, I'll give them a ballpark or a direct figure, depending on a whim, to be honest.

 

[Arnwyn]

Do they know skill check DCs before they decide to use the skill?

Not always, but usually, yes. If it's in the PHB, then we consider it to be a fairly standard use of the skill, and the PCs should know the odds. If it's something that's clearly an unknown, though, then the DCs are kept hidden.

Do they get to know the save DCs they're rolling against?

No.

Do they get to know which spell an NPC threw at them?

Not immediately, no. "Roll spellcraft, you lazy git!"

Do you tell them the AC of a combat target?

Never.

Or get them to roll and you tell them whether you hit or not?

Yep, that would be it.

Do you tell them the total dice rolls or just whether the NPC failed or suceeded at whatever they were trying to do?

Just need to tell them whether the NPC failed/succeeded. They don't need to know the number result, which would have no benefit except for slowing down the game.

Would it make things too wargamey?

I think so, but that's just me.

 

[Savage Jim]

I prefer that players (which includes me in those rare instances that I actually get to play) focus primarily on role-playing and decision making/action declaration, stearing away from calculating odds, metagaming, and rules-lawyering.

As a GM, I take the following actions...

Do they know skill check DCs before they decide to use the skill?
No. In addition, I don't use DCs but CDRs (Check Difficulty Ratings). These are calculated as:

A = DC - 10

The PC's Skill Check is then opposed by a roll of 1d20 + A.

I don't use this for DCs under 10.

Do they get to know the save DCs they're rolling against?
No. These are also handled as above.

Do they get to know which spell an NPC threw at them?
No. In addition, spells may have a different "look" depending on the order/fellowship/brotherhood/etc. of the spellcaster, so a spell may be described, but it may not get the same description that it was given previously when another spellcaster cast it.

Do you tell them the AC of a combat target? Or get them to roll and you tell them whether you hit or not? Something else?
I use Defense Ratings (gained by Level + Dex), with DR for Armor/Natural Armor. The Defense Rating is rolled to oppose the Attack Roll.

Do you tell them the total dice rolls or just whether the NPC failed or suceeded at whatever they were trying to do?
Succeed or fail.

I also make all rolls in the open, although the total number of modifiers is rarely known to the players.

 

[kigmatzomat]

Most unopposed skill DCs are known from the beginning. After about 2 rounds of my 17th level players swinging at a foe I tell them the AC to speed things up. Ditto for save DCs of repeated effects (dragon breath, gaze powers, etc). Generally in a few rounds they get the gut reaction of "holy crap, I rolled a 15 and failed!" or "Poor goober, I hit you with a 2 on my third off-hand attack" and I want to speed things up. After that I want to spend my time on providing a cinematic visual for the dice rolling, not being Mentat the Magnificent calculating their every result.

 

[Zappo]

Do they know skill check DCs before they decide to use the skill?
It depends on whether the character has a way of estimating the action's difficulty. They can generally know the exact DC of a Jump or Climb check. They can generally never know even the approximate DC of a Spot or Sense Motive check. They can sometimes know whether a Knowledge DC is high or low.

Do they get to know the save DCs they're rolling against?
No. Though, if they've done the same save multiple times (eg, against ghouls), I may eventually tell them the DC since I figure their characters would eventually get a solid estimate of the power of the effect.

Do they get to know which spell an NPC threw at them?
Yes. With a Spellcraft check. Of course, the players can recognize common spells from my description of the effect; they don't need Spellcraft to understand what "a fiery bead strikes the ground behind you and explodes in a huge ball of flames" means.

Do you tell them the AC of a combat target? Or get them to roll and you tell them whether you hit or not? Something else?
They roll and I tell whether they hit or miss. If they ask, or if it sounds cool, I tell them whether they hit the armor or missed entirely - this is pretty simple: if they would have hit touch AC, then it was the armor that deflected the blow. Otherwise, they really missed.

Do you tell them the total dice rolls or just whether the NPC failed or suceeded at whatever they were trying to do?
I don't tell anything about NPCs' rolls.

 

[Saeviomagy]

As a GM, I take the following actions...

Do they know skill check DCs before they decide to use the skill?
No. In addition, I don't use DCs but CDRs (Check Difficulty Ratings). These are calculated as:

A = DC - 10

The PC's Skill Check is then opposed by a roll of 1d20 + A.

I don't use this for DCs under 10.

Ouch. I guess noone ever risks jumping or climbing in your world then.

 

[Wikid Klown]

I let them know very little. I tell them what kind of spell they're hit with if they get hit, that's about it. Most of my PC's have had DM experience, so it puts me at a disadvantage, but I'm ok with it, since they don't get to sit there and stare at their books, and they don't really memorize the stats for anything that uncommon (like they know the AC of an orc, zombie, the weak stuff they get/have gotten a lot of), I tell them if they're close or not, but not by how much. I also roll in secret, I think that it doesn't show as much threat if they fight something with high modifiers, and gives more thrill to it. They don't know the DC's, but they know that if it's more than 10 off, they get screwed, wheather they find out immidiately or later (like a failed listen check for misinformation). They know about the NPC's, but only if they're allies, otherwise they don't know.

 

[Li Shenron]

This is a very interesting topic, sometimes I have been thinking about it already. Usually I keep hidden whatever I can, just in case but really it would be good to try out being more open.

Do they know skill check DCs before they decide to use the skill?

This is something we discussed for a while long ago. In a way it would make very sense for someone who is trained in one skill to be able to evaluate how difficult a task is, at least vaguely. Obviously that cannot be applied to every skill: a climber may be easily able to evaluate if a surface is beyond his capabilities, but you definitely cannot say the same about search, listen and spot checks for example.

However we never tried to play that PCs can know the DC beforehand.

When it's up to me to DM I at least suggest to the player (if they ask) whether a task seems trivial, feasible, very challenging, etc... expecially if there's a dire penalty for failure.

One exception that I do (and here I understand that many DMs would never allow this) is that I always tell the player if Take10 would result in "failure with bad consequences". This can be explained in-character as starting the task and halting as soon as you notice that you're making a mistake. IOW, it's like disallowing Take10 in this circumstance, because it will be fatal. This just because I think Take10 is meant as an advantage given to the PC, and should not become a trick.

Do they get to know the save DCs they're rolling against?

It's possible that I have slipped out the save DC sometimes, but it's probably not good if they are allowed a way to modify their ST after knowing the DC (feats, reroll-abilities, ...).

Do they get to know which spell an NPC threw at them?

Generally not. It's more fun to describe the effects and the visual manifestations (which I sometimes scramble as will Spell Thematics) that to just name the spell. But eventually when the DM is tired, there's usually no problem in doing that, unless it's an illusion obviously, or unless someone is trying to counterspell.

Do you tell them the AC of a combat target? Or get them to roll and you tell them whether you hit or not? Something else?

It's very easy to figure it out after a few rolls, but best not to tell beforehand so at least they have a couple of rounds of mystery Also often there are abilities such as dodge or selective protections which make the AC different depending on who's the attacker.

Do you tell them the total dice rolls or just whether the NPC failed or suceeded at whatever they were trying to do?

Normally just the resulting effect.

I'm seriously considering moving towards a very 'mechanics in the open' style of GMing. I think it'd be interesting to see how this worked out... would certainly give the players a very concise view of the world around them? On the other hand, would seeing 'under the hood' kill off the mystery of the game? Would it make things too wargamey?

Well you can try and see what happens I don't think the game would be spoiled at all, it will simply become more strategic and less random once you know better which action may be moot and which other may really help. Combat will definitely be less mysterious and more wargamey, but you can keep up the mystery with the story and will many other things (I mean, if all mystery in someone's game depends on not knowing numbers in combat, that's a pretty worrying situation...).

 

[Gez]

I'm curious to know how much of the game mechanics DMs let the players know about...

Do they know skill check DCs before they decide to use the skill?
Often.

Do they get to know the save DCs they're rolling against?
Sometimes.

Do they get to know which spell an NPC threw at them?
No, they have to make a Spellcraft check. Reason: the counterspelling mechanism.

Do you tell them the AC of a combat target? Or get them to roll and you tell them whether you hit or not? Something else?
The longer a combat lasts, the more likely I end up giving them the AC so that they can tell me whether they hit or not themselves.

Do you tell them the total dice rolls or just whether the NPC failed or suceeded at whatever they were trying to do?

I don't give NPC die roll result, except when it has special effects (like a natural 20 in combat).

I'm seriously considering moving towards a very 'mechanics in the open' style of GMing. I think it'd be interesting to see how this worked out... would certainly give the players a very concise view of the world around them? On the other hand, would seeing 'under the hood' kill off the mystery of the game? Would it make things too wargamey?

IME, it doesn't. Now I won't claim my experience is universally true for everyone.

I roll my NPC die either in the open or behind the screen, without much rhymes or reasons -- most of times, it doesn't matter. I try neither to keep the mechanics hidden from the players, nor to exhibit it. So I do both, without much caring.

 

[mhacdebhandia]

Do they know skill check DCs before they decide to use the skill?

Yes, presuming that they have a way of judging the difficulty. Like other posters have said, Jump or Climb checks are pretty reasonable things to judge before trying them; Knowledge checks wouldn't be. Passive skills like Spot and Listen would be checks I would roll for the characters myself; I can't imagine running a game where I didn't have an accurate copy of everyone's character sheet.

Do they get to know the save DCs they're rolling against?

Sure. It's not very likely to help them.

Do they get to know which spell an NPC threw at them?

I would describe the effect and let the players draw their own conclusions. For example, an explosive fiery burst is probably a fireball, but they don't know if it was Maximized or Empowered or whatever, or what level the caster was and how many dice I rolled for the damage. Spells which don't have an overt effect would need Spellcraft checks to identify, and of course Spellcraft checks are necessary for counterspelling.

Do you tell them the AC of a combat target? Or get them to roll and you tell them whether you hit or not? Something else?

I see no reason not to reveal this information after they've tried. I might start off by verbally describing the effect of their first few attacks - if they just barely hit above the AC, I could say "You just manage to land a blow past his expert defenses/on a vulnerable spot in its tough hide/et cetera". I think it's also worth distinguishing between different reasons why you're missing - armour, natural armour, dodge feats, and so forth. So after a few rounds of this, I'd just reveal the AC for the sake of speeding things up.

Do you tell them the total dice rolls or just whether the NPC failed or suceeded at whatever they were trying to do?

The latter. I think players have the right to know whatever their characters would know, and other information if it speeds up combat or would be a reasonable conclusion to draw - revealing save DCs from a fireball is one thing, for example, but if they didn't know they were poisoned I would ask for a Fortitude save and not explain why or what the DC was.

Regardless of how many numbers the players know, I think it's important to describe things with a bit of flavour.