The main NPCs of Borderlands sit down to play a role-playing game similar to Dungeons and Dragons while trying to help Tiny Tina come to terms with the death of Roland. You are their player characters and run and gun through a fantasy world. The normal bandits and robot enemies are replaced with skeletons, dragons, orcs, golems and such.
Its a bit random, but it is very well written and references everything from Game of Thrones to The Lord of the Rings. Very entertaining to play-through, although it gets quite difficult at times.