Dungeon Dice Monsters is a game that (according to Yami Yugi) "is just like duel monsters". It was invented by Duke Devlin. Duke submitted his project to Pegasus and played a game with him in order to show him the potential of the game. Pegasus won that game easily making Duke surprised. It is probable that Pegasus used his mind reading tricks to know how to play but according to Yami Yugi it was more like Pegasus was playing the game he invented in the first place. According to Duke, the game is not like Duel Monsters because his game "has dice in it".