Private Dexter Keith, a soldier fighting aliens on an asteroid, is caught in the blast of a time bomb that sends his mind back through his own lifetime.
You got to understand, a phase grenade messes with your mind, grunt.

Variants

(1)
  1. “The Swimming Pool of the Universe” by Nick Cole, in Synchronic: 13 Tales of Time Travel (edited by David Gatewood, David Gatewood) May 2014.
    2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by Nick Cole