Microsoft has been counting on "Gears of War," which went on sale on November 7, to steal some thunder from the recent launches of rival gaming machines from Sony Corp. (SNE) and Nintendo Co. Ltd.
Game sales also are important because Microsoft loses money on each Xbox 360 machine it sells, so it relies on game sales to make the business profitable.
Microsoft said earlier this month that "Gears of War," which puts players in the role of a futuristic soldier battling invading aliens, had booked the biggest number of pre-orders of any of its games since 2004's "Halo 2," the second installment of the flagship franchise for the original Xbox.
Pre-ordering is the retail practice in which consumers pay money in advance to ensure a copy of a game on launch date.
Still, "Gears of War " did not come close to matching the draw of "Halo 2," which sold $125 million — roughly 2.5 million copies — in its first 24 hours of availability.
"Halo 2," however, had the benefit of building on the successful formula of its predecessor, and it also came three years into the life of the original Xbox, meaning there was a bigger pool of potential buyers.
By contrast, "Gears of War" is an all-new game and arrived just a year after the Xbox 360 hit the market. Its price tag is 20 percent higher than that of "Halo 2" when it was launched.
Microsoft also said subscriptions to its Xbox Live online gaming service have increased because of "Gears of War." Paid registrations per day for the online gaming service have climbed 50 percent since the game's debut.