MMORPG.com previews Fallen Earth:

You enter the world of Fallen Earth as a clone that was brought back from the dead by a LifeNet scientist. She is the one who is helping you escape the Hoover Dam complex, which incidentally is a cleverly disguised tutorial in the shape of your very first quest. Unfortunately the original functional facilities have been destroyed by Alec Masters, who was later hanged by one of six game factions named CHOTA (Children of The Apocalypse). And so you are actually a clone without the customary given gift of immortality, since your DNA is damaged. From the very beginning you learn that you are actually dying. As you manage to escape the Hoover Dam, the next active mission given to you is all about stopping your demise. The entire game plot and the storyline unfold from here on.