About 2.5 million people have bought the latest Halo 3: ODST game ($60, for Xbox 360) since it was released two weeks ago, a nice reception for a game that doesn't star Halo main man, the Master Chief. Instead, players control a squad of futuristic special forces known as Orbital Drop Shock Troopers (ODSTs) deployed to fight off the enemy forces of The Covenant attacking Earth.

Already Halo 3: ODST has generated more than $125 million in sales, continuing the success of the franchise that had sold more than 27 million so far. "That's pretty good for a game that most called an 'expansion pack,' " says analyst Michael Pachter of Wedbush Morgan Securities.