Pokémon Gold Version is a role-playing game developed by Game Freak and published by Nintendo for the Game Boy Color, first released in 1999 in Japan and later in other regions. As the second generation of the Pokémon series, it takes players to the new Johto region, where aspiring trainers collect Gym Badges, challenge Gym Leaders, and aim to become the Pokémon League Champion. The game adds 100 new Pokémon, expanding the Pokédex to 251 species, and introduces a day-and-night cycle that influences which Pokémon appear and when they evolve. A breeding system lets players hatch Pokémon Eggs to obtain rare or unique creatures. Gold also supports trading and battling with Pokémon Red, Green, Blue, and Yellow via link cable. With its deep content and fresh mechanics, Pokémon Gold became one of the best-selling and most acclaimed titles on the Game Boy Color.