Guild Wars 2

Perhaps killing the elder dragons was a very big mistake…
Dark forces behind our comprehension have been unleashed, forces that were restrained by the magic of these mystical and powerful creatures. A threat like the world has never seen before is coming and it threatens to destroy the very fabric of life. It rests now upon your shoulders to rescue us all.

The player will have to travel to the past, to the old continent of tyria, the way it was before Lions Arch was destroyed. In a mission to alter specific events in the past that lead to the ultimate demise of all the races, and save the world.

The player will revisit old locations and relive key GW1 moments. Be present when king Alderbern unleashes the Foe Fire, presence the destruction of ascalon, or its very foundation. Witness (and participate) how the Mursat imprisoned the titans.
Travel through different eras, completing different missions, and saving the world.

……..

The time travel could be implemented through a special asura gate, which the player can help to build, adding additional playability to the expansion.
The world could be destroyed right as the player escapes through the gate, adding a more dramatic effect. Now failure would be out of the question.

If you like this idea, post your comments so Anet can see this thread.