There is world called �emartial arts realm�f or �emartial arts land�f. Nobody knows when it was created or how people in that world lived together. However, the genre of martial arts has unwittingly become an inseparable part of our daily lives. Less attention may be paid to the world than before in terms of volume. However, the contents themselves have been continuously developed to meet user�f expectations. A host of authors have described the martial arts world in the form of a novel, which has been also introduced to us through movies or dramas. In other words, there are various types of media through which the heroic world can be expressed realistically. d.o is a full 3D online martial arts game describing such a world. When reading a martial arts novel, a reader usually stretches the imagination in his or her own way, where he or she becomes a hero or heroines, fighting enemies who are threatening the peaceful world for his or her guild, overcoming crises to obtain gifts from the gods, and finally becoming the head of the world. d.o will help you, the player, enjoy a realistic fantasy world spreading before you, differentiated from existing martial arts worlds described only in the imagination.