The second installment of Cardtography is up at Kobold Press.
We didn’t choose cards as our randomizers because they’re somewhat room-shaped. That’s a happy coincidence. The real reason is because they have information embedded on them, and we can use that information in all sorts of useful ways.
A playing card has two obvious bits of information: suit (clubs, diamonds, hearts, spades) and value (1-13). Those aren’t, however, the only way to classify their information. Suits can be reduced to red or black, and value can be looked at as 1-10 plus face cards. With so much encoded information to play with, we can combine bits to derive other values and create further groupings: odd black cards, for example, or red face cards.