Yu-Gi-Oh! Duel Monsters 4: Battle of Great Duelist is a Game Boy Color game and the fourth installment in the Duel Monsters series of Yu-Gi-Oh! It features 900 different cards and was released as three seperate versions, each having a unique selection of cards that can be used during the story and traded with the other versions. This version focuses on Seto Kaiba and the god card Obelisk the Tormentor.