We have done this. Many year ago, we had a situation in a Vampire game.

Characters where in a night club and one of them was on the outside and saw a truck that was going to crash against it. The meta-gamer told then that his character was going to the restroom. The Storyteller asked him why in that precise moment his character (who didn't even pee) was going there, and he said his character could do whatever he wanted.

The ST didn't allow it, and I think he did right. Metagaming cheapens the game and the story, making characters do things incoherent with the plot. It also lessens the challenge. If your players metagame, you will have an illogic, incoherent story.

That doesn't me fighting against metagaming is a task only for you. In our game group all players can warn when they think another one is metaplaying. We ask frequently "How do your character know that?", or "Why is he suddenly changing his action?", or even "Are you sure that is not metagame?".

We set a system of penalties and rewards that we happily haven't need to use. Establishing the system and thinking about the problem has made everyone aware, and reduced much the metagaming.

So, talk to your players and explain why the metagame makes everyone's game worse. Then tell them you need their help, and come up with means to avoid metagame. And as a last resort, with actions extremely illogic, don't allow them (IMHO).

We have done this. Many year ago, we had a similar situation in a Vampire game.

The characters were in a night club; one of them was on the outside and saw a truck that was going to crash against it. The meta-gamer then said that his character was going to the restroom. The Storyteller asked him why at that precise moment his character (who didn't even pee) was going there, and he said his character could do whatever he wanted.

The ST didn't allow it, and I think he did right. Metagaming cheapens the game and the story, making characters do things incoherent with the plot. It also lessens the challenge. If your players metagame, you will have an illogical, incoherent story.

That doesn't mean that fighting against metagaming is a task only for you. In our game group all players can warn when they think another one is metagaming. We ask frequently "How do your character know that?", or "Why is he suddenly changing his action?", or even "Are you sure that is not metagame?".

We set a system of penalties and rewards that we happily haven't needed to use yet. Establishing the system and thinking about the problem has made everyone aware, and much reduced the metagaming.

So, talk to your players and explain why metagaming makes everyone's game worse. Then tell them you need their help, and come up with means to avoid metagaming. And as a last resort, with extremely illogical actions, don't allow them (IMHO).