Copywrite Question

Copywrite Question

Does a company have a copywrite to things like the story and quest?  NPC names?  I was just curious if someone took a game and completely redid everything but the quest text, is that illegal?  Take for instance if someone created a game like Ultima or Everquest and kept the names of the cities, NPCs and storyline does that go against their rights to the game? I know the client and assets are protected, but what about everything else?