Simple is considered a franchise, as well as a well-selling one - 48th best-selling of all franchises, ever.
That places it above franchises like Half-Life, Warcraft, Diablo, SimCity, Nintendogs, and Metroid, in sales. Perhaps not well-known in the Western world, but it has still earned its spot.
In other news, DAMNIT I MISSED THE END AGAIN. >=(
SW-5120-1900-6153