Fortune Article

Twelve years ago Microsoft bought Bungie, a small, Chicago-based maker of hard-core games. Outraged fans claimed its upcoming Halo game would be watered down. Not so much. After seven titles and 43 million copies sold, the Halo series it created is a profit machine. (Estimated at under $40 million, the Bungie buy is arguably Microsoft's most successful ever -- sales have reached an estimated $3 billion.) Here is a look at the massive moneymaker's evolution (and total sales). HaloDate: Nov. 15, 2001
Sold: 6.43 million Coinciding with the launch of Microsoft's first console, Halo: Combat Evolved sold 1 million units in just under five months, a record.

Halo 2

Date: Nov. 9, 2004
Sold: 8.49 million The midnight unveiling drew thousands of fans to stores. The company sold 2.4 million copies in the first 24 hours.

Halo 3

Date: Sept. 25, 2007
Sold: 11.6 million Revealed by a beaming Bill Gates at the E3 trade show in 2006, this became the most popular title to date.

Halo 4

Date: Nov . 6, 2012
Sold: 6.5 million* Microsoft's Xbox has begun to show its age. The company needs this title to be a hit and help drive crucial holiday sales.

Halo: Microsoft’s $3 billion Xbox game

Halo 2

Halo 3

Halo 4