The original Pokémon games launched in Japan on February 27, 1996, establishing the date later celebrated as Pokémon Day.
Pocket Monsters Red and Green were developed by Game Freak and published by Nintendo for the original Game Boy. Their release began the Pokémon video game series, although the franchise soon expanded into cards, animation, merchandise, and films.
The launch was originally planned for December 21, 1995, but it was delayed because related products were not ready. The Japanese versions were Red and Green; the international releases used Red and Blue instead. February 27 is therefore associated with the franchise’s anniversary, rather than the date of the anime’s debut or the first trading-card release.