You must walk around fields, smashing the gentle creatures of earth. Eventually, you'll gain enough experience to get that job working IT for an evil corporation. Then, you backstab your way up the corporate ladder, thrusting a subtle dagger of justice through the underbelly of incompetence. Then, when the last body falls to your elevated wit and guile, you can look back on all of the beautiful things you've destroyed with a wistful eye, knowing that the story line is almost over, and there will most likely be a beautiful cut scene before the credits roll and you have to buy into another game.
What? Unhappy ending? Not every game can be Katamari Damacy or some other piece of fluff. Judging by the games we play, we spend ninety percent of our time killing things for no apparent reason. It's the circle of life, baby. Only the circle is actually a line segment defined by narrative traditions.
So here's the respite from line segments, just pause the game and let the music loop around for a while- truly unending satisfaction. At least until you get annoyed. That can happen pretty quickly. So level up quick! Look for the next loop! Some of them are pretty good and merit the wholesale murder of creatures that are beneath you!