Pokémon Gold and Silver began the second generation of Pokémon games in Japan in 1999. They were released for the Game Boy Color and expanded the series beyond the original Kanto adventure.
The games introduced the Johto region and 100 new Pokémon, raising the cumulative Pokédex total from 151 to 251. They also added new gameplay systems, including Pokémon breeding, held items, a day-and-night cycle, and a real-time clock linked to the game world.
Gold and Silver were designed as sequels rather than unrelated spin-offs. After the player completes the Johto storyline, the games allow a return to Kanto, where many locations and characters from the first generation can be revisited. This large post-game area helped make the titles especially notable among main-series releases.
The international launch happened later: Australia and North America received the games in October 2000, while Europe received them in April 2001. Those dates are sometimes mistaken for the Japanese debut.