Liubo - Confucius thought the game was a waste of time, but it's cost many hours of research!

About Liubo, from BoardGameGeek:

Ancient Chinese game dating back to at least 400BC or perhaps even as far back as 700 BC. The game maybe connected to the later Xiangqi, Nyout and some race games like Ashtapada, representing cosmological and religious patterns, used also for divination. The rules are forgotten, but many pictures and artifacts, even records of single divinations made with the same board, have been found, and there is a playable "reconstructed" version by chess-expert and author Jean-Louis Cazaux http://history.chess.free.fr/liubo-rules.htm. The board is a square with an unusual pattern of lines and angles on it, equally on each side. There is also a central square. The moves of the six figures (five "pawns" and one "king") of the two players are determined by throwing marked sticks, probably not by only counting some marks but also interpreting and calculating the throw according to some rules derived from the Yijing. Winner is the one who captures all of his opponent's stones.