David Young's wife has been murdered and the events have left David unable to recollect the memories of her death, but he now has the ability to time travel. In D4, players take control of private investigator David Young and must travel through time in order to find evidence about the murder and attempt to undo it. In order to go back in time, David must find certain objects that give him the ability to project himself back to a certain point in time before the murder. D4 has cel-shaded graphics and plays out much like a playable novel.
D4 is directed by Hidetaka Suehiro (also known as Swery 65) who is best known for his work on Deadly Premonition. Fans of Deadly Premonition will be happy to know that D4 has tons of references to Swery's past games (Deadly Premonition and Spy Fiction). The title of D4 is an acronym for "Dark Dreams Don't Die". D4 is an episodic type of game and the first collection of episodes was released on September 18, 2014.