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 2 remake of "DOA" and "DOA2" for the Xbox with a greatly improved graphics engine. As it was created after "Dead or Alive 3", it takes elements and mechanics from both its original iteration and successor. The action of 3D-axis movement is as free-formatted as "DOA3", and Hitomi, as well as Tengu are now playable characters (albeit outside story mode), but other elements have been kept intact from "DOA2". The biggest set of changes instituted in "Dead or Alive Ultimate" are online play over Xbox Live and the inclusion of slopes, which are a type of environmental hazard. Dead or Alive