Anyway - it's driven by a deck of cards. The players are dealt a number of cards each. The GM states the obstacle and sets the difficulty for that scene. 'There's a timelocked door, difficulty 8'. The players then get to play cards from their hands. Each card (or combination of cards) is a flashback scene. So, if I play the Nine of Diamonds, then I get to narrate a flashback scene that somehow bypasses the challenge of the timelocked door. 'Aha, I say, I bribed the sysadmin of the building to change the time on the computer clocks'.
Diamonds are flashback scenes related to cash, clubs to violence, hearts to interpersonal and spades to gadgets. The cards are placed in a stack of some sort, so you build up a backstory as you play (if I play Card X behind Card Y, then Scene X took place chronologically before Card Y, even though Card Y was played first).
Kings are scenes relating to a male NPC who is closely related to one of the other PCs. Queens are scenes relating to a female NPC who is closely related to one of the other PCs.
Jacks are scenes relating to a child NPC who is closely related to one of the other PCs.
Aces are...something clever.
There's some mechanic to represent the plan going wrong, in which case you can't flashback your way out of it. Stuff. Ninjas. More thought needed.