Pocket Monsters Midori (Green), released in Japan, is a prototype version of Pokémon Red and Green. Its gameplay is very similar to the final released versions, but with some notable differences in the Pokémon available, locations, and even some slight variations in the game mechanics.  The game was developed by Game Freak and published by Nintendo for the Nintendo Game Boy.

Pocket Monsters Midori (Japan) (Rev A)

Pocket Monsters Aka (Japan) (Rev A)