Mahjong Bishoujoden Ripple

As gods created the Earth, a divine woman, blessed with three powers, descended upon it. These three powers were: the power of eternal youth; the power of making thoughts into reality; and finally, the power to bestow these powers on others. The goddess lived in a forest, and her powers created living beings. Eventually, the human beings forgot about the goddess, abandoned the sacred forest, and her story became myth... until one day, the goddess is is threatened by those humans who want to invade her world and the world of other spiritual beings. Only one person can stop the madness - a young, pretty female warrior named Ripple. Her skill in the game of mahjong is the only way to stop evil!!..

Ripple is essentially a mixture of RPG and the Chinese game mahjong. Like in most Japanese RPGs, Ripple walks on the world map in top-down fashion, visiting towns to buy supplies, chat with NPCs, rest, etc. Instead of participating in "normal" battles, however, Ripple plays mahjong with her opponents. Better stats and new combinations are acquired by winning these games, new areas are unlocked and the story advances after successfully winning pre-set mahjong encounters.