Weird Computer Science: Dwarf Fortress

The seven embarked from the Dwarven mountain homes in early Autumn.  They laid clam to a rocky hillside near a calm brook and began excavation.  It began as a mud and dirt hovel, but it had soon grown into an expansive subterranean complex.  Migrants from lands far away began to hear tale of the fortress and arrive daily to find good fortune of their own.  From the crowd distinct personalities emerge; heroes, drunks, caretakers, leaders.  The deep earth produces endless riches.  Hearts are content here, stomachs are full.
 In the dead of winter, a vile dark curtain falls across the frozen hillside.  The enemy has arrived, a black, twisted army of villains and viciousness.  The white snow topped hills melt under red rivers of hot blood.  Swords clash and hammers smash.  The fortress is now a tomb.

http://www.bay12games.com/dwarves/