I *think* mythusmage is saying that the events of a roleplaying game should consist of players living out the fictional lives of their characters in a world created by the GM. Dramatic things will just sorta happen if you do that, right?
I disagree. "Drama where it naturally occurs" is kind of a dodge. No matter how much everyone at the table wants it to be so, the characters and the game world don't exist. They are fictional constructs. To the extent that dramatic, interesting things happen in the game, they didn't "just happen"; they were created by an interplay between players and GM. I think people are advocating that this happen unconsciously rather than consciously.
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I don't want to get into defending GNS (really, I don't) so I'll just talk about "Story Now" by itself as a concept. Story Now isn't about playing out a precreated story -- that "Now" part is important. It's about the players and GM setting up situations in game that lead to meaningful decisions. The whole point of Story Now is that it's not deterministic.
I've run several games that were about the theme "What would you do for power?" and the theme informed my decisions rather than dictating them. Rather than have things "just happen", I set up character-relevant situations where there was a benefit and cost to gaining power. Game prep is about setting up issues characters will have to deal with, but have no one right answer.
Story Now isn't for everyone, I know. I just like it 'cause it works for us.
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I totally agree that there should be no "set story" the GM has in his head at the start. To the extent there is a story, or theme, or whatever, it's created during play by characters making decisions. I just personally prefer to have the whole group mindful that we want interesting things to happen consistently during play, rather than just hoping it'll happen eventually if we "live in the game world" enough.