[quote=@Pair of Hearts]
[@Tarquin]
This is why I prefer giving individual quests on top of solving the case. "You don't achieve that? You still lose. Oh, btw, one of the player's goal is to destroy yours, so watch what crap you say."
[/quote]

Well it's not a bad idea, but I don't think it really solves the problem. If you were to present such a situation to a metagamer of the same kind I'm thinking of, would they not simply cheat at both the case and the individual quest? Like, "My character suddenly finds a note that reveals the true mystery, and a MacGuffin that trivializes his personal quest! What luck!"

And I'm certain the same player would be the type to instantly godmode any character that threatened their success. Then they'll bitch and moan when you tell them it's against the rules and leave in protest of your fascism etc etc....