From the review:
Once Upon A Time is a game in which the players create a story together, using cards that show typical elements from fairy tales. One player is the Storyteller and creates a story using the ingredients on her cards. She tries to guide the plot towards her own ending. The other players try to use cards to interrupt her and become the new Storyteller. The winner is the first player to play out all her cards and end with her Happy Ever After card.
The second edition, published in 1995, features an expanded card set.
The third edition, published in 2012, features multiple changes, including new artwork by Omar Rayyan, a new card set, and a simplified rulesheet.