I suggested dice, as well as 'gold' coins (though I'm not sure how expensive they would be or how hard it would be to get a limited production run), and a couple other things.
In D:OS 2 you can talk to ghosts. That's how the Ouija board came up; it was something unique and kind of game related, that could have some game related artwork. There were some other game related suggestions, which were presumably too expensive, too delicate to ship or were thought to not have enough appeal.