Which original Pokémon game version was never released outside Japan?

Pokémon Green was the original game version that was never released outside Japan. In Japan, Pokémon Red and Green launched together for the Game Boy on February 27, 1996.

A Japanese Pokémon Blue version followed later as a revised special edition. Its artwork, script, and programming became the basis for the international releases, which were titled Pokémon Red and Blue rather than Red and Green.

This creates a common source of confusion for international players. The overseas Red version is paired with Blue, while the Japanese launch pair was Red and Green. The Japanese Green cartridge therefore has a distinct historical role in the franchise's origin.

Pokémon Green did receive later forms of recognition. A redesigned version of the Japanese game was represented through Pokémon FireRed and LeafGreen on the Game Boy Advance, but the original 1996 Green release itself remained Japan-exclusive.