What were the names of the first Pokémon game versions released in Japan?

The first Pokémon game versions released in Japan were Red and Green.

Nintendo launched Pocket Monsters Red and Green for the Game Boy on February 27, 1996. The two versions were substantially similar but contained different Pokémon, encouraging players to connect their systems and trade.

International releases used Red and Blue instead. The overseas Blue version was based on the later Japanese Pokémon Blue release, which featured revised artwork, updated dialogue, and other refinements. This is why many international fans know Red and Blue as the original pair.

Yellow was released later and was inspired more directly by the television anime, with Pikachu following the player character. It is therefore inaccurate to call Red and Yellow the first Japanese pair, even though both titles belong to the original generation.