Saving Schroedinger's Cat

In the 25th century, deep under the Earth's shattered surface, the dying remnants of humankind live in a dwindling Colony devoid of Nature and only one can travel to the past to save humanity from its dark fate.

Clinging to life underground, after a cataclysmic all-out nuclear war, the remains of the human race are desperate for a way to change the past. Harnessing the power of an artificial wormhole, their only hope to avert global annihilation is to travel back in time and alter the discovery of nuclear fission.

Humanity's future rests on the unlikely shoulders of Proteus. Born with a unique genetic mutation, scientists discover that he is the only one capable of surviving the ravages of time-travel. After decades of preparation, Proteus is sent backwards to early 20th century London... but Time doesn't want the past to change and it pushes back.

To complete his mission, Proteus must manipulate the course of history, all the while battling enemy agents and avoiding the forces of Time, if he's ever going to save the future from the past.