Compact. It'll fit in your purse or in a jacket, or a shirt. I don't know what you're wearing, but it will probably fit in the clothes. If not, there's always your hand.
Simple. It's not overly complicated, so anybody can play. Children, Teens, and the rest of us. Ghosts probably. Super intelligent apes. Dolphins maybe.
Fun. It's fun, even if you don't win. Sometimes keeping someone else from winning can be just as sweet.
Strategic Play. Don't let the simplicity fool you. There's layers to this game. Like an onion, or a Moon Pie.