Microsoft have announced that the Halo series has now sold 50 million units since it began in 2001 on the original Xbox.
Eight Halo games have been released to date and all have been a FPS except one, Halo Wars, which was released in March 2009 and was a strategy game.
More than five billion hours of Halo have been played on Xbox Live and I’m sure I speak for most people when I say that that is easily understandable. All games in this series are fantastic!
[Source: Gamespot]