The Poetry of Time
A ship arrives on Earth and immediately begins the process of sterilizing the planet, killing all flora and fauna. All military resources have been used, but nothing could withstand the alien technology.
A man, after killing his wife and children to spare them suffering, is sent back to a distant past on Earth. There, fueled by his hatred, he changes his worldview and induces profound changes in ancient society. Soon, all the peoples of the Earth have a single leader, and like a well-calibrated machine, they develop technologies to seek revenge in the future.
He must destroy the invaders and restore the normal course of life in the future, but to do so, those who were born in this new timeline would have to disappear. This is the poetry of time: everything changes when time itself is altered.
-- Nils Verd