The series' is based on Alchemy. In the first game, young Adept (means who can control Alchemy) Isaac and his friends travel to stop Alchemy from returning to the world. But in the second book, players' task is let the Alchemy return the world. 30 years later, the first two games character's children start a new adventure.
Golden Sun and Golden Sun: the Lost Age are both in IGN's Readers Choice Top 100 games.[1][2]