Fun blog article: Story elements in games

For your enjoyment and thought process food, Classy Gamer has provided a good article on the many different plot and emotional devices used in video games. I would add "giant monsters" and "Ridiculously hard to get items" to the list, but this is a good starter list:

http://classygamer.blogspot.com/2009/08/top-10-story-elements-in-videogames.html