So, the variant: you start off with two ending cards. Whenever it's your turn, you must play one of your ending cards before you can play a story card. You can just play the ending card and start tying it into the story, or you can talk for a few sentences before playing the ending card, to connect the current story to the ending. No one can interrupt you before you play your ending card, but you can't play any of your story cards either.
Once you play the ending card, your turn continues as in vanilla: you play story cards and try to get to the point where you can play your second ending card. If someone interrupts you, you must draw a story card and an ending card (so you begin each of your turns with two ending cards).
If someone's story gets to the point where you could play an ending card, you can interrupt with the ending card and start your story from there. (This actually happened.)
Since OUaT stories jump around a lot anyway, it's not difficult to use an ending card to close one thread of the story or to spawn a new thread. The additional constraint is generally what I need to feel
comfortable making up an OUaT story.
Update: See comments for feedback from OUaT co-author James Wallis.
(7) Sun Mar 19 2006 01:09 Once Upon a Time Variant:
We hung out with Brendan and Maria all day and played games. We came up with this Once Upon a Time variant which fixes what I think is the biggest problem with OUaT: the underuse of ending cards. You get a million story cards that have single concepts on them, and there's an equally large deck of ending cards, each containing an entire plot point. This other deck is cooler but you go through it at 1/100th the speed.