In Yu-Gi-Oh! Forbidden Memories, Nitemare is known to be the creator of the Shadow Games. He is sealed away in the Forbidden Ruins, only to be awoken when the 7 Millennium Items are brought there.
When Heishin awakens DarkNite, he attempts to order him claiming it is part of the pact, but Darknite says that he does not recall making a pact with Heishin. When Heishin begins to plea with DarkNite, he quickly grows tired of the conversation and turns Heishin into a card. Finding it to be nosiest and ugliest card he ever created, DarkNite burns it saying it doesn't deserve a place in his Deck.
DarkNite then turns to the prince and Seto saying that they would make nice additions to his Deck. Seto reminds the prince about the Millennium Item Cards. The prince then holds out the cards forcing DarkNite back. Unable to fully hold him back, the prince is left to duel DarkNite. After losing once DarkNite refuses to accept his defeat and turns into Nitemare demanding another Duel. The prince proceeds to defeat Nitemare, sending him back to where he came from.