"Reach already surpassed the all-time highest record for Halo 3 concurrent users on LIVE. Woot!" said a Bungie developer, in a post on the company's Twitter page.
The developer did not specify how many gamers logged in to play Halo Reach at the same time, but the numbers were likely significant.
As of midday Wednesday, the basic, $59 version of Halo Reach was the top selling video game on Amazon.com, while the $79 Limited edition held the fourth place spot.
A $399 bundle that features a Halo-themed, 250GB Xbox 360 console and wireless controller, as well as the basic edition of the game, was the eighth best seller on Amazon's list.
The Legendary edition, which includes 10" character figurines designed by Todd McFarlane and sells for a whopping $149, was in ninth place on Amazon's real-time roster of top-selling video games.
Microsoft and retail partner Best Buy held launch parties Monday night in New York, Seattle, and London, England to mark the game's release. At the New York event, crowds lined up for blocks around the city's famous Times Square area to be among the first to purchase the game.
Halo Reach, an Xbox 360 exclusive, is billed as a prequel to the original version of Halo. "Halo Reach follows the story of Noble Team, a squad of heroic Spartan soldiers as they make their final stand on planet Reach, humanity's last line of defense between the terrifying Covenant and Earth," according to Microsoft.
The game features a new graphics and audio engine that offers enhanced visuals and sounds over its predecessors, Microsoft said.