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, including adding the "Dark Magician" as a monster, and hacking into KaibaCorp's computer system.
When 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 transferred to Domino High School, the school that Yugi and his friends attend. He quickly became popular and impressed girls with a number of dice tricks. Jealous, Joey Wheeler challenged Duke to a game of Duel Monsters. They agreed to the stakes 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 brand-new Deck.
The Duel took 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 televised his game with Yugi. Having not played Dungeon Dice Monsters before, Yugi struggled at first and Duke gained an early advantage. However, Yugi made a few comebacks and ultimately won using the "Dark Magician" that Pegasus had added.
Duke then apologized to Yugi, having realized that Yugi was an honest game player and determined that he wouldn't have cheated against Pegasus. He began 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 comforted Duke, assuring him that Dungeon Dice Monsters had the potential to become a great game. Soon after, Duke received word from Industrial Illusions in the form of an email stating that they would be helping produce Dungeon Dice Monsters, and had agreed to make the game global.
Duke was trapped in Noah Kaiba's Virtual World along with the other participants aboard Seto Kaiba's Battle City Quarterfinals blimp. Along with Serenity and Tristan, Duke Dueled Nezbitt of The Big Five with the stakes being ownership of his body and the ability to return to the real world. At one point during the game, after drawing the Magic Card "Dice Dungeon", Duke turned the arena into a Dice Monsters Dungeon, confidently telling Nezbitt, “You don’t know me, but let’s just say I know a thing or two about dice.”
Battle City finals
Duke helps Joey when he collapses from his Duel with Yami Marik, and he cheers for Yugi during the Battle City finals. He parts with the group at the end of the finals, slipping Serenity his phone number, much to Tristan's anger.
Waking the Dragons
During the Waking the Dragons arc, Duke was again reunited with the group after saving Rex Raptor and Weevil Underwood while they were lost in America. He helped them when they convinced him that they were friends of Yugi's. He assisted Yugi, Joey, and Kaiba against the Doma Organization and took part in a Duel with Rebecca Hawkins against Valon. For most of this Duel, his cards involved increasing the strength of Rebecca's dragon monsters. Despite summoning a powerful dragon, Valon beat them with his Armor monsters. Duke and Rebecca's souls were not taken after their loss as Valon never played the "The Seal of Orichalcos" during their Duel. However, he was unable to give the gang support later on because of being in another place during Yugi and Kaiba's Duel with Dartz.
KC Grand Championship
Duke tagged along with Yugi and his friends during the KC Grand Championship. During the final episode, he said that he has a date with Serenity, and Tristan and Joey attack him for even saying so.
During the Dawn of the Duel arc, Duke helped take care of Solomon Muto and contacted Yugi's friends and other important people, such as Maximillion Pegasus, about Yugi's absence. He accompanied Yugi to the Ceremonial Battle. He witnessed the Pharaoh's departure to the spirit world and the sealing away of the seven Millennium Items.
As there's no mention of Duke working with Pegasus in GX, it's highly likely Dungeon Dice Monsters' popularity fell (much like in the real world) in the following years, forcing Duke to end the game series.