From the manual:
"Welcome to the world of YARI - one of the lost wonders of the earth!
From the cradle of civilization to the dawn of "civilized man," many collective societies have risen and fallen, leaving only mysterious traces of their cultures, struggles, and wisdom. Like all civilizations, they, too, had much to teach the generations that followed, but those secrets have remained lost in sand and stone, long forgotten... until YARI.
YARI is not just a game.
YARI is a way of thinking.
YARI is logic, strategy, and wisdom.
YARI is a secret that you, too, can share, an arcane pathway into the development of the mind.
YARI is a universal language without words, without sound.
YARI links your mind to your opponent's - a contest of wills."
YARI is... basically... Sorry! using shells for dice and a few fairly nice bits.