Ending a first entry in a potential series can be fickle. You want your game to be a complete story, yet you also want to leave room for the possibility of a sequel. Despite being part of the Final Fantasy brand, Square seemed unsure if Final Fantasy XI would succeed. As their first MMO, there was no guarantee.
If you play the basic Final Fantasy XI story, it largely wraps up with the original arc. You defeat the Shadow Lord and help solve a threat to your home nation. However, the game did well enough in Japan for an expansion pack to be made. Rise of the Zilart aimed to build onto the original’s story line.
So how do you continue a tale that has ended? When you first arrive in the port city Norg, you faint and remember an alternate ending to the original game. They explain your forgetfulness as your character going through shock.
For a game that eventually expanded to have seemingly endless possible story threads to follow, it’s one of the more bizarre events in the game.
Final Fantasy XIII suffered from the same problem when Square Enix started creating XIII-2. With nowhere to go, they just forcibly shoved a time-travel story into the world so they could change the ending of the original.
(Header Image Source: Final Fantasy XI Wiki)