Microsoft has announced that Halo 2 on Xbox sold over five million units worldwide and is now most popular game in the history of Xbox Live.

The game hit the five million in sales in three weeks, a figure the original took two years to achieve, and looks set to cement the game as the most successful media launch of all time.

Halo 2 had an opening weekend that saw it hit $100m in sales -- more than any Hollywood blockbuster to date.

According to Bloomberg, Microsoft expects to ship 20 million units by June 2005.