The first generation (Japanese: 第一世代 first generation) of Pokémon games, known among older fans as the color generation or the chromatic generation due to the names of the versions released, is the initial set of four Pokémon games released.
Beginning with Pokémon Red and Green, and later joined by third version Blue and special edition Yellow in Japan, the Generation I games were developed beginning as early as 1990 from an idea that Satoshi Tajiri had thought of and pitched to Nintendo with the help of Shigeru Miyamoto. The inspiration for many of the key mechanics introduced in this generation came from Tajiri's childhood interest in bug collecting, with the trading system between two Game Boys being thought of when he imagined a caterpillar crawling across the Game Link Cable between two systems.
This generation was localized into English, with initial attempts to keep the Pocket Monsters name for international use blocked due to the Monster_in_My_Pocket franchise leading to the release as "Pokémon". Further alterations made in the localization included the combination of Red, Green, and Blue into the English versions of Pokémon Red and Blue, using Red and Green's wild Pokémon encounter lists but Blue's slightly improved graphics. The simultaneous release of the games and anime led to an almost-overnight surge in popularity, cementing the Pokémon franchise firmly as a Nintendo mainstay alongside Super Mario and The Legend of Zelda.
Two battle arena games were released in this generation: the mostly-incomplete Pokémon Stadium (Japanese), which went unreleased outside of Japan and only allowed use of 42 Pokémon, and the improved Pokémon Stadium, which featured several special battle modes and a Gym Leader Castle where players could take their fully-trained teams for matches against the Kanto Gym Leaders, Elite Four, and Champion.
The games proved popular enough that, eight years after their original release, they received remakes in the form of Pokémon FireRed and LeafGreen, as the original versions are incompatible with Generation III and onward.
The storyline of the Kanto region is contemporaneous with the Hoenn story of Generation III, as revealed by details in both the Hoenn-based games as well as the Pokémon later remakes of Generation I. The storylines of the Generation II and Generation IV games occur three years after this generation, with details about this link explicitly noted throughout the Johto-based games.