Microsoft's Halo 3 racked up $170 million in sales on its first day of availability, making it the hottest-selling title in video game history.

Microsoft said late Wednesday that the game's sales easily surpassed first-day sales for Halo 2, which previously held the record. Halo 2 launched in 2004 and posted $125 million in sales on its first day.

Halo 3, which hit shelves on Tuesday, also broke industry records for presales. Retailers took more than 1.7 million preorders for the game, which runs on Microsoft's Xbox 360 console. More than 1 million gamers played the game online over Microsoft's Xbox Live system on launch day -- another record for the software maker.

Microsoft is hoping that Halo 3 will boost demand for the Xbox 360, sales of which plunged 60% year over year in the fiscal fourth quarter. Not only are Xbox sales important to Microsoft in and of themselves, they're also key to the company's goal of becoming a leader in the broader home entertainment market.

Microsoft envisions the Xbox as a platform through which consumers can play games, watch movies, listen to music, and download paid content.

Halo 3 is a so-called first-person shooter featuring Master Chief, a biologically enhanced supersoldier who has to blast his way through a futuristic, 3-D landscape to survive and accomplish missions. He's countered at every turn by a shadowy terrorist group called The Covenant.

Despite the sales records, Microsoft's Halo 3 launch was not without problems. The company conceded that the packaging on the $70 Limited Edition of the game can scratch the discs inside. Microsoft has added Halo 3 Limited Edition to a disc replacement program it started after some Xbox 360 buyers complained that the units were scratching their game discs.