We couldn't resist the double play on words - two kinds of playing, and cards/chords. But this deck of 12 different cards, representing the twelve notes of the chromatic scale, can be used to play a whole range of different games. Educators can have students play a range of different games exploring the construction of chords, beginning with the simplest and progressing to complex jazz harmonies, or tone row which challenges your memory as you play a game that follows Schoenberg's principles.
And even on their own, they can be used as flash cards by students!