Ruin Arm tells the story of a young boy named Arm, who lives together in Arff Village together with his father Borgan, his sister Linda, and the talking bird Lucia. Proud of the warrior traditions of their family, Borgan sends Arm to retrieve a powerful sword from the depths of the dungeon Arff. When Arm returns home, he finds the village attacked by soldiers from as hostile empire. His father loses his memory, and he has to find a magical herb to cure him. The king of Rondium and his court magician send Arm and Linda on a quest to find out more about the attack, and Arm discovers the secrets of the ancient Mediom empire and its evil emperor.
This is an action RPG in which you control Arm and his party. You can either let the computer AI handle the actions of the other characters, or control them on your own, one at a time. In battles, characters have their own attacks: Arm uses physical attacks, Linda casts magic, etc. The dungeons are complex, and many of them have puzzles that you can solve by making two characters co-operate.