"FireRed" and "LeafGreen" were first announced in September 2003 as upcoming remakes of the original "Pocket Monsters Red" and "Green" games that were released in Japan in 1996. Game director Junichi Masuda stated the new titles would be developed around the idea of simplicity, as the game engine was a slightly modified version of the one used in "Pokémon Ruby" and "Sapphire". As a result, "FireRed" and "LeafGreen" were made fully backward compatible with "Ruby" and "Sapphire", allowing players to trade Pokémon between games.