In Startling Odyssey, the player takes the role of a young boy named Leon. One day, his home villages is attacked by monsters. His best friend is killed, and the most powerful magician of the village is turned into stone and abducted by the monsters' leader. Leon receives the blessing of the village elder and begins his quest to avenge the death of his friend and to defeat the demonic forces that threaten the land.

The game is a rather traditional Japanese RPG, with all the familiar ingredients: Leon (and his companions who later join the party) roams the world map, entering towns and dungeons, buying equipment and items, and engaging randomly appearing enemies in turn-based combat. The battles are viewed from first-person perspective. Characters can use regular attacks as well as magical spells, and the battles can be also set on Auto.