 Its sequel , Halo 2 was released on the Xbox on November 9 , 2004 , and later for Windows Vista on May 17 , 2007 . For the first time , the game was released in two different editions : a standard edition with just the game disc and traditional Xbox packaging ; and the Collector 's Edition with a specially designed aluminum case , along with an additional bonus DVD , extra booklet , and slightly different user manual . Halo 2 introduced new gameplay elements , chief among them the ability to hold and fire two weapons simultaneously , known as " dual wielding " . Unlike its predecessor , Halo 2 fully supported online multiplayer via Xbox Live . The game uses " matchmaking " to facilitate joining online matches by grouping players looking for certain types of games . This was a change from the more traditional " server list " approach , which was used to find matches in online games at this time . Upon release , Halo 2 became the game played by the most people on the Xbox Live service that week ; it retained this title for over two years – the longest streak any game has held the spot . 
