AP – The role-playing game was invented by Americans (thanks, Gary Gygax, for “Dungeons & Dragons”), but it’s always been somewhat of a niche product among U.S. video-game enthusiasts. Sure, RPG series like “Final Fantasy” and “Diablo” have their stateside devotees, but they’re far outnumbered by fans of shooters like “Halo” or sports games like “Madden NFL.”