''To most gamers, Ninja Gaiden conjures up an image of an ultra-violent, ultra-difficult ninja game. This isn't the case for the new addition to the series, Ninja Gaiden: Dragon Sword for the Nintendo DS. While Dragon Sword is unique in its presentation and gameplay, it doesn't deviate from franchise's core values of super-quick ninja fighting.
In Dragon Sword, Ryu's female ninja apprentice, Momiji, is kidnapped, and he must venture to rescue her. Along the way, he figures out that the kidnapping is linked to his Dragon Sword and ends up battling a whole slew of demons along the way.
To play the game, you hold the DS sideways like a book, and everything - including movement, guarding, and attacking - is performed via the touch-screen. The one exception is guarding, which is done by pressing any face button. The DS's microphone is also incorporated into the gameplay; in addition to other puzzles, you'll have to yell to wake up an old man and blow into it to extinguish flames. It's one of the few games on the DS where using the mic isn't gimmicky and actually makes sense.''