The Coming of the Quantum Cats can - given different social conditions - develop completely different character traits (timid or assertive, benevolent or predatory, etc.) The title refers to the famous thought-experiment known as "Schrödinger's Cat", where the outcome of a real-world event depends on a quantum event. By some interpretations, the real-world object, in this case a cat, must be in two states simultaneously until it is observed. However, the story is more closely related to the many-worlds interpretation of quantum mechanics where all possible outcomes of an event occur, each in its own parallel universe. The same concept was treated, somewhat more pessimistically, in
Dead or Alive Ultimate game mechanics, new game content, online multiplayer capabilities, and the inclusion of Hitomi as a playable character. "Dead or Alive Ultimate" is a compilation game that includes a remade version of "Dead or Alive 2", with re-developed graphics and new stages for the Xbox gaming system. It also includes the original Sega Saturn version of the first "Dead or Alive", with smoothed graphics, but lacks the additional content received in the later-released North American PlayStation version (no Bass or Ayane characters or extra costumes). Both editions include online play. "Dead or Alive Ultimate 1" is essentially identical to its original