How many years did Pokémon Red and Green take to develop?

Pokémon Red and Green took six years to develop.

Satoshi Tajiri first conceived the Pokémon idea around 1990 after considering how Game Boy link cables could connect players. Game Freak then worked on the project until the Japanese release in February 1996. The long development period reflected the ambition of building a large role-playing game with creature collecting, battles, trading, and a hidden world of secrets.

Development was difficult financially. Game Freak reportedly came close to bankruptcy, and the team worked for years while Nintendo and other partners helped the project reach completion. Creatures Inc. also invested in the project and received a share of the franchise rights.

The six-year figure is about development time, not the period between the Japanese and international launches. Pokémon Red and Blue arrived in North America in 1998, but those versions were localizations and adaptations of the earlier Japanese games.