In 1981, when he was sixteen years old, Tajiri won a contest sponsored by Nintendo rival Sega for a game design concept. A year later, in 1982, Tajiri and his friends formed a gaming magazine by the name of Game Freak. A friend and contributor to Game Freak was Ken Sugimori, who would later become the illustrator and designer of all of the Pokémon images, as well as the human characters and other aspects of the games. Throughout the 1980s, the Game Freak magazine had modest sales, and became quite popular among the gaming crowd. Originally, the magazine was written by hand, but as it grew more popular Tajiri began having it printed professionally. A typical issue cost ¥300 (around US$3.00) and was approximately 28 pages long.
In the early 1990s, when Tajiri first saw two children playing together with Game Boys using the Game Link Cable, he imagined insects crawling along the cable between the two systems. As he thought about the capabilities of the Game Link Cable, his idea for Pokémon grew, as he wanted to give modern children the chance to hunt for creatures as he did as a child. He pitched the idea for Pokémon to Nintendo, and although they didn't fully understand the concept of the game, he was given some initial funding anyway and concept work from another game design studio, Creatures, Inc.. Tajiri spent the next six years working on Pokémon. Shigeru Miyamoto, the man behind Mario, The Legend of Zelda, Pikmin, and Donkey Kong, was assigned to help in the development of the initial versions of Pocket Monsters, Red and Green. During this time Tajiri came to admire Miyamoto as a mentor. As a tribute to Miyamoto and Tajiri, the main character of the games and his rival have "Satoshi" and "Shigeru" among their default names, while the main character of the anime, Ash Ketchum, and his first rival, Gary Oak, are named the same, respectively.After six years of development, Pokémon Red and Green Versions were completed. Although the Game Boy's hardware was becoming outdated, the game still grew steadily in popularity because younger children could not afford brand-new console games so they turned to the inexpensive Game Boy games.The success of Pokémon led to various manga adaptations, an anime, and more Pokémon games and spinoff games.
After the creation of Pokemon HeartGold and Soulsilver Tajiri stepped down as his role of producer and became the exceutive producer where it didn't have to put much input and could step back and have more time with his wife and newborn son. After stepping down he did tons of interviews telling his startup with Gamefreak and his afterfore mentioned exit from the franchise. No duobt without his determination and hard work the gaming world would not be the same with out him.