Mm – if people really don't want to talk to each other, you can't force them.¹ But I would hope that, in the icebreaking context the game's being played, they would be prepared to buy in to the idea of having enough conversation to plausibly be "convinced" – whether that be by weight, number, or persistence of argument is probably best left up to individual preference.

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1 Well, you can, but not within the terms of the Geneva Conventions.