Multi'Verses
Another game/set, this time in which the game worlds are each fully implemented copies of worlds from fantasy books (or original worlds) where the story is told by scripted NPC’s so the game follows the books exactly. THEN you throw in a number of completely random and unrelated lot, with non-story-related plots. Each of these plots is made in such a way as to lead you to a goal and on the way let you observe the story of the basis.
A short example would be Tolkien’s universe, in which the game portrays the story of The Hobbit, (but could be scaled to include Lord of the Rings, and the other works) and the player gets to play a hobbit until Bilbo’s party, then switch to a Grey Elf whilst in Rivendell. Another they could play is a Dwarf before the fall of Moria, or an orc whilst the Balrog fights Gandalf. etc etc.
It only really works in the greatest of epics, the most believable of worlds.