Dead or Alive Ultimate is a compilation fighting game developed by Team Ninja and released by Tecmo for the Xbox in 2004. It is a collection of the two previous games in the series Dead or Alive and Dead or Alive 2. It marks the only game to be a compilation game.
The compilation contains the Sega Saturn version of Dead or Alive and an enhanced remake of DOA2 which utilized the Dead or Alive Xtreme Beach Volleyball graphics engine and offered DOA3 game mechanics, new game content, online multiplayer capabilities and the inclusion of Hitomi as a playable character. The game requires Xbox Live in order to play online, and includes 12 different game modes, 15 different characters from the Dead or Alive series, as well as bonus content for Dead or Alive 3.
With the December 14, 2006, backwards compatibility update for the Xbox 360, the Xbox release of Dead or Alive Ultimate can now be played on the Xbox 360.
Source: Wikipedia, "Dead or Alive Ultimate", available under the CC-BY-SA License.