[WARNING: Mild Spoilers ahead for the “Black Ops 2” single-player campaign.]

David Petraeus may have stepped down as CIA director amid the scandal surrounding his extramarital affair last week, but he’s already been re-enlisted for active duty in one place—the dystopic near-future of “Call of Duty: Black Ops 2,” which was released on Midnight Tuesday to millions of eager gamers and fans of Activision’s iconic military shooter franchise.

The...