Mew was the hidden Pokémon Satoshi Tajiri added to the original games to spark rumors.
Mew was not part of the original public promotion for Pokémon Red and Green. Tajiri secretly included it in the game data, and its existence became a powerful source of speculation among players. The creature was numbered 151, after the 150 Pokémon that could be encountered through the ordinary game structure.
Because Mew was difficult or impossible to obtain through normal play, players traded stories about hidden areas, glitches, and secret methods. Nintendo later used an official event to distribute Mew, turning the rumor into a real promotional phenomenon.
Mew and Mewtwo are often confused because both are connected to the first generation and to the first Pokémon movie. Mew is the elusive Mythical Pokémon associated with the hidden game data, while Mewtwo is a genetically engineered Pokémon created from Mew’s DNA in the story.
The mystery surrounding Mew helped keep attention on the games after their initial release and strengthened Pokémon’s culture of discovery and exchange.