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.
Everything you were as Adeptus Astartes was a pale preamble to what the Deathwatch now demands of you. Where others have failed, you cannot. The greed of many allowed the Ruinous Powers passage, and the flaws and failures of mortal minds let them slip into hiding, biding their time and growing in their power. But now, as a planet begins its descent into depravity, your Kill Squad arrives to defeat Chaos and bring Imperial Order.