"Pokémon Blue" is a role-playing game developed by Game Freak and published by Nintendo, released in limited quantities in selected regions of Japan on October 15, 1996, and rolled out nationwide on October 10, 1999. One of the Generation I entries in the Pokémon series, it runs on the Game Boy. In the game, players take on the role of a ten-year-old Trainer embarking on an adventure to challenge eight Gym Leaders, defeat the Elite Four and Champion, and become the Pokémon Master. Players also catch and train various Pokémon to complete the Pokédex, with 151 Pokémon in total, some of which are version exclusives obtainable only through trading. Building on "Red" and "Green," "Pokémon Blue" features bug fixes and adjusted Pokémon encounter rates. Its success not only cemented Nintendo's dominance in the handheld market but also laid the foundation for the future of the Pokémon series.