Apexer System

As humanity was barely surviving in the aftermath of nuclear armageddon caused byWW 3 that began with the Ukrainian-Russian war an alien taskforce came over and started exterminating the last remmenants of humanity until there was nothing left...
But as fate would have it a certain bored omnipotent being who was currently sitting in his barracks from all universes encompassing author's race decided to give a certain someone a second chance and see what will happen after a soldier from the future returns back to the past and receives an Apexer System.