Bones was the name of a card game played by the inhabitants of The Monastery of Uthgar. Not much is known about how the game is played. There were many different styles of cards, each one with a different bone on it, in the shape of a little monster. They could be arranged in "sets", styled after structures of the human body, such as the Skull Set, for example. The were released in packs of 15, which cost 1 silver each. The packs were randomized, and one would have to buy many packs to complete a set.
It is unknown who created the game, but we do know that a witch named Connell made some of the cards, and sold them to students of The Monastery of Uthgar, such as Skud Derringer and Chopper.