On November 16, 2004, Valve released Half-Life 2, the sequel to the original game. Half-Life: Opposing Force and Half-Life: Blue Shift were released on November 10, 1999, and June 12, 2001, respectively. Two expansions, taking place during the same events as Half-Life but centring on characters other than Gordon Freeman, were released in the next few years. Half-Life was the first title in the series, as well as the debut title of Valve Software. In addition, there have been two expansions to the original Half-Life title and a number of non-canon spin-offs. In each game the player obtains the role of the theoretical physicist Gordon Freeman. A final episode, Half-Life 2: Episode Three, has been confirmed to be the next installment of the series.
Two of these games, Half-Life and Half-Life 2, are full length titles, while two more, Half-Life 2: Episode One and Half-Life 2: Episode Two, are shorter, episodic titles.
