Alternate-worlds jaunt from the author of Singularity’s Ring (2008).
Uncomplicated Ohio farm boy John Rayburn's goal is to study physics at college—until another John Rayburn shows up. John's rather battered-looking double explains that he carries a device that allows him to travel between alternate universes. The double—Prime—shows John designs for some moneymaking devices (like Rubik's Cube) that don't exist in John's world. The travel device seems simple enough to operate, and John agrees to try it. Bingo! The device works, but with one fatal flaw—John can't return home. Prime, obviously, knew the device was broken and conned John in order to steal his life. After various adventures in other worlds, John decides to settle down in an acceptable world and learn physics, with the eventual goal of repairing the device. Meanwhile, Prime runs into difficulties: he marries the girl of his dreams, Casey Nicholson, after getting her pregnant, while his plan to sell millions of “Rayburn's Cubes” runs into legal problems, and Ted Carson, the local bully, causes trouble. In his new home, meanwhile, John studies physics, enjoys an on-again, off-again relationship with alternate Casey, steers clear of another Ted—and almost against his will, finds that he's “invented” pinball, which is unknown there. John's variation of the game proves a big hit, but attracts attention from a ruthless community of exiled travelers, who also make money by introducing unknown technology—and will stop at nothing to obtain a device to enable them to return home.
Well executed but all too familiar, with a late plot twist suggesting it will mutate into an interworld hunter-killer series. Your move.