C.A.R.D.S. Core Rules presents everything needed for impromptu or simple roleplaying except for a standard deck of cards. The deck is divided into suits and distributed among the GM and one to three players. If more than three players are participating, a second deck is used. The GM and each player receives all the cards of one suit. The GM also retains the Jokers.
Game play proceeds along a narrative-only fashion until a conflict situation arises (e.g., combat, as there is no skills system). Combat is then resolved by playing cards. Cards are discarded when played, or discarded when "lost" to a higher card. Winning cards return to the winners' hand. The core rules deal almost exclusively with this mechanism.