Yu-Gi-Oh! Duel Monsters (遊戯王デュエルモンスターズ, Yūgiō Dyueru Monsutāzu) is the second Yu-Gi-Oh! video game, following Yu-Gi-Oh! Monster Capsule: Breed and Battle. It is the first game in the Duel Monsters series and the only game released for the Game Boy. It was published in Japan by Konami on December 16, 1998.