Pokémon is a series of games developed by Game Freak and Creatures Inc. and published by Nintendo as part of the Pokémon media franchise. First released in 1996 in Japan for the Game Boy, the main series of role-playing video games (RPG) has continued on each generation of Nintendo's handhelds. Games are commonly released in pairs—each with slight variations—and then an enhanced remake of the games is released a few years from the original release. While the main series consists of role-playing games, spinoffs encompass other genres such as action role-playing, puzzle, and digital pet games. It is the second best-selling video game franchise worldwide, next to Nintendo's own Mario franchise.GenerationsAll of the licensed Pokémon properties overseen by The Pokémon Company are divided roughly by generation. These generations are roughly chronological divisions by release; when an official sequel in the main RPG series is released that features new Pokémon, characters, and gameplay concepts, that sequel is considered the start of a new generation of the franchise. The main games and their spin-offs, the anime, manga and trading card game are all updated with the new Pokémon properties each time a new generation begins. The franchise began its sixth generation with Pokémon X and Y, which were released worldwide on October 12, 2013.