In the anime, Duke invented Dungeon Dice Monsters and visited Maximillion Pegasus to demonstrate the game shortly before the Duelist Kingdom tournament. Duke was impressed by Pegasus' skill at the game. Pegasus himself enjoyed the game and approved of the creation of Dungeon Dice Monsters, wanting to expand it further. Upon Pegasus' request, Duke allowed him to make additions to the game, like the "Dark Magician" as a monster and also hacked into KaibaCorp's computer system.
However, after Pegasus disappeared after being defeated by Yugi Muto in the Duelist Kingdom tournament, Duke blamed Yugi for his disappearance and believed that Yugi must have cheated to beat a gamer as good as Pegasus. He swore to get revenge on Yugi whom he believed didn't deserve the title "King of Games".
After the Duelist Kingdom tournament, Duke opened the Black Clown (a rival game shop to the Kame Game) and was transferred to Domino High School, the school that Yugi attends. He quickly became popular and impressed girls with a number of dice tricks. Joey Wheeler became jealous and challenged Duke to a game of Duel Monsters. They agreed to the stakes which were that if Joey won, Duke would close his shop and if Duke won, Joey would be his slave for a week. Having been the runner-up in Duelist Kingdom, Joey was certain that he would win. However, not having his own Deck, Duke insisted that they play using cards straight from Booster Packs. Joey agreed and they each created a Deck.
The Duel takes place at the Black Clown. Duke televised the event in the hopes of humiliating Joey. Over the first few turns Joey knocked chunks out of Duke's Life Points while leaving his own unscathed, but Duke managed to turn the Duel around and take out all of Joey's Life Points in one turn.
In keeping his end of the bargain Joey became Duke's slave. Duke further embarrassed him by having him dress in a dog suit. Yami Yugi was disgusted by his treatment of Joey and challenged Duke to a Duel to release Joey. Duke was not interested in Dueling and challenged Yugi to a game of Dungeon Dice Monsters. If Yugi won, Joey would be free again, but if Duke won, Yugi was to swear on his grandfather's life to never play Duel Monsters again.
Duke also televises his game with Yugi. Having not played Dungeon Dice Monsters before, Yugi struggles at first and Duke gains an early advantage. However, Yugi makes a few comebacks and ultimately wins using the "Dark Magician" that Pegasus added.
Duke realizes that Yugi plays honestly and determined that he wouldn't have cheated against Pegasus. He starts to worry that the televised game was going to be bad publicity as it made him look like a bad person. However, Yugi and his friends comfort Duke, saying that Dungeon Dice Monsters has the potential to become a great game. Duke soon receives word from Industrial Illusions, saying that they will be helping produce Dungeon Dice Monsters and have agreed to make the game global.
Duke helps Joey when he collapses from his duel with Yami Marik, and cheers for Yugi during the Battle City finals. He parts with the rest at the end, slipping Serenity his phone number, much to Tristan's anger.
Waking the Dragons
Duke helps Yugi, Joey, and Kaiba against the Doma Organization in the Waking the Dragons arc. He also took part in a duel with Rebecca Hawkins against Valon. Most of this duel, his cards revolved in increasing the strength of Rebecca's dragon monsters. Despite getting a very powerful dragon, Valon beat them with his armor cards. However Duke and Rebecca's souls were not lost as Valon never played the Seal of Orichalcos. However, he was unable to give the gang support because of being in another place during Yugi and Kaiba's duel with Dartz.
KC Grand Championship
He also tags along with Yugi during the KC Grand Championship.
During the final episode he says that he has a date with Serenity, and Tristan and Joey attack him for even saying so.
During the Dawn of the Duel saga, he helped take care of Yugi's grandpa, and contacted Yugi's friends and other important people such as Maximillion Pegasus about Yugi's absence (offscreen). He came along with Yugi to the Ceremonial battle.
Duke's first Deck is made up of cards that he used in a Duel against Joey Wheeler, in which both duelists agreed to open several packs of cards and simply use whatever they pulled from them. All the cards are from the Pharaoh's Servant expansion of the actual card game.