Let's say that you decline an Xbox One pre-order, buy the Xbox 360 version of a big game this fall and promptly regret that you haven't gone next-gen. Are you hosed? Not necessarily: GameStop is launching a promo that will let you upgrade to an Xbox One edition of a game for $10 or less. Provided you're a PowerUp Rewards member, GameStop will offer at least $50 in credit if you trade in an Xbox 360 copy of Assassin's Creed 4, Battlefield 4, Call of Duty: Ghosts, FIFA 14 or Madden 25 and buy its Xbox One equivalent at $60. There are additional catches, of course. You'll have to buy a given Xbox 360 title within 30 days of its launch, and you'll have to use the credit before the end of the year. Even so, the promo could minimize buyer's remorse -- and save some Xbox One buyers from waiting until November to play the titles they want.