Yakuman Game Boy

In Japanese Mahjong, yaku (Japanese: å½¹) is a condition that determines the value of the player's hand. It is essential to know the yaku for game strategy, although the knowledge is not mandatory. A player must have a minimum of one yaku in their hand in order to legally win a hand. Each yaku has a specific han value. Yaku conditions may be combined to produce hands of greater value. The game also features dora, that allow a hand to add han value, but that cannot count as yaku. Altogether, a hand's points value increases exponentially with every han a hand contains.

- Wikipedia