I don’t know what it is, but I love cards. I think it stems from my parents, who were avid Bridge players. We always had several decks Bridge cards lying around. I like how they feel in your hand, how they smell, how they sound as you shuffle them. When I first discovered that people had been producing sets of cards for everything from project management to game design and of course gamification, I was a happy man! I own several of these kinds of decks now and love them all.