What were the original Japanese Pokémon game versions released in 1996 called?

The original Japanese Pokémon versions were called Pocket Monsters Red and Green.

Game Freak released Pocket Monsters Red and Green for the Game Boy in Japan on February 27, 1996. The two versions shared the same main adventure but contained different Pokémon, encouraging players to connect their systems and trade.

Japan later received Pocket Monsters Blue as a revised version with updated artwork, dialogue, and programming. The international releases were based on that revised version, but they were renamed Pokémon Red and Blue rather than Red and Green.

This regional naming difference is the source of a frequent anniversary misunderstanding. Green was the original Japanese counterpart to Red, while Blue became the counterpart most international players knew. Pokémon Yellow was a later enhanced edition associated with Pikachu and the anime.