The initial letters of the clues spell "READ DIAGONAL". Every clue hints at a particular card game. In order, they are as follows.
- HEARTS
- PINOCHLE
- BIG TWO
- EUCHRE
- CRIBBAGE
- MAO
- DURAK
- BRIDGE
- WHIST
- GIN RUMMY
- CANASTA
- BRISCOLA
Reading down the diagonal of each set gives the phrase "HIGH CARD WINS", which clues the answer WAR.