Bawylie
A very OK person
Well, I'm not going to try to argue my points any further because I think we've mostly talked this thing through for now, but I am genuinely curious how you would handle the last example I posited, where only one character was told the secret location of a genie lamp, and a different player "just happened" to look in the extremely unlikely place where the lamp was hidden to claim it first, even though there was no way that character would have had that knowledge.
What would you do, if anything, about that. Would you consider it a form of meta-gaming, or not? Would you think that the first player was treated unfairly when he role-played according to an unspoken rule of what characters know and don't know, when the other player simply ignored that and decided to use the meta-knowledge to his advantage? Again, this is not a challenge; I am interested in what you'd think of that.
Cool. Good question.
So, one of the things I do in my games is a sort of preamble, talking about how I like to run things at the game.
For the cooperative games, one of those things I tell players is that anything I say out loud at the table as DM is to be treated as common knowledge to all. If you hear it, your character knows it. We assume your characters are nearly constantly keeping each other up to date. Another thing I say is that I have no interest in issues of player/character knowledge divide and will not spend any table time on it, so you should play that out as far as you're interested in doing so.
That tends to work out just fine and nearly everyone plays in good faith. So I'd address the dilemma you posed largely by ignoring it until and unless it became contentious. At which point I'd rely on one other part of my preamble. Which is that PVP style actions are resolved by the target of those actions.
Player A knows the "secret"
Player B scoops player A.
Later they fight about it. Since B stole from A, A gets to determine how that worked out, ultimately.
It comes down to that age old rule among children sharing something: "You cut it, but I get first pick."
Now all that's maybe way outside how some people prefer to play. But in practice, this sort of thing rarely comes up. Because the rule is in place, and everyone hears it every time they play, there isn't much incentive to try something anti-cooperative. It won't work unless everyone else is buying-in.
Major benefit for me is that people adjust their own behavior and I don't have to waste table time on frivolous disputes. And that's a huge priority for me we can waste time when we're not stealing it from 3 or 4 other people. Not during game time though. That's wrong.
-Brad