first, he added non-linear gameplay. you can choose to complete part of the story in any order that is safe for you, building up to the final moment where you confront sauron, and he need not necessarily face you in the first piece of the game. a lot of the game feels like this, with \"choices\" giving you the illusion of control while controlling how your character responds to you. it's a smart tactic for keeping the player engaged and turning every choice into an effect on the story. second, fargo created a storyline subplot for the hobbits while they slept. gandalf informs the hobbits as they explore the world for rest. at some point, they get a phone call: \"the company\" is in trouble. gandalf entreats you to go to the rescue. it's a way to effectively gain some control over what is happening at a distance. it's a neat way to make the hobbits feel like an important subplot without committing the old fallacy of star-crossed lovers.
gandalfs contribution is key to the story. with him on the case, the company has a chance of survival. with a scant three weeks left to save the hobbits, gandalf gets them safely to greenwood the near-perfect setting of mirkwood. they also help the villagers organize their defense, putting them on the right side of history. the sequence where the hobbits leave greenwood is one of the smoothest in the game. i'd love to see a version that looked more closely at the story in the book, and whose opening moments more strongly resembled the book.
gandalf sacrifices his own life by sending his body to the shadow of mordor. to understand why, it helps to know gandalf has been fighting the shadow of mordor since its fall at the end of the first age. gandalf is an old man, he has always fought this evil.