Editing Sin City: a Game to Kill For (section)

== The System ==
The system is Diceless, running off playing cards exclusively, fitting to the theme of the setting. Each player has his own deck of cards, shuffles it, and sets aside the jokers (red and black) for their wild cards. At the beginning of each scene (of which there can be multiple within a single session) players and GMs shuffle their decks, draw 5 cards, and add the two jokers to their hand. They then take the top card of their deck, reveal it, and find out who goes first by who has the highest card. 

Each active player's turn, the player can take a number of actions that they choose that is equal to the number of cards in their hand (six, including the joker, only one of which can be used in a round). an action is any specific use of a skill (shooting a gun, seducing a person, etc). The Downside of taking all six actions is that you have exhausted your ability to react on other player's turns. When you use a card for action on your turn, you play it face-down and then describe what you are doing. the players effected then place one of their own cards face-down and describe their reactions. everything is resolved when the active player reveals his card; if they show a red card, it can only be beat with a higher card, if they show a black card, it can only be beat with a lower card. Aces, however, beat all, (except in the case when the active player plays an ace and the reactive player does the same, because active players always win ties).

Reactive players then reveal their cards and find out if they succeeded from preventing/avoiding whatever the active player did. If in combat, and they failed they will take damage. At the end of a turn the reactive players replenish the same number of cards spent from their hands and the active player keeps the remainder of his cards as his options for reacting. the whole idea is to keep rounds interesting with a sense of risk and reward with each new action. 
 

Jokers are used as a constant, and can always be played (but only once until their next turn) and use the character's relevant skill value instead of a card in their hand. 

That is literally the most complex part of the game, and the game's mechanics almost in their entirety explained in three paragraphs. Give it a shot sometime.