Before Unnatural's title was locked in, it went by a lot of other names. Here are some of the book titles that were axed along the way:
Gen2K
The Last Alive
Unmatched
The Hidden Ones
Those Who Remain
Those Who Are Hidden
When the Births Stopped
Babes No More
Barren
Barren World
Hope for the Barren
Over and Out
The City Spy
Reassignment
Leaving the Last Clean City
The Untouched