Complex sentence: In "Golden Sun", the player plays as protagonist Isaac and his companions as they set off into the world of Weyard to prevent a group of anti-heroes from releasing a mysterious power called "Alchemy" to the world.
Split into simpler sentences: In "Golden Sun", the player plays as Isaac and his friends. They set off into the world of Weyard to prevent a group of anti-heroes from releasing Alchemy to the world.