Bungie's Halo: Reach has achieved the astonishing feat of becoming the biggest game Microsoft has ever released.
The sales success means Reach is bigger than Microsoft's record-breaker Halo 3.
Microsoft Game Studios boss Phil Spencer had already revealed the science fiction shooter generated $200 million in the first 24 hours of release in the US and Europe.
And we know Reach is the biggest US entertainment launch of 2010, beating the three-day opening weekends of films Iron Man 2, Alice in Wonderland and Toy Story 3 in a single day.
But this latest revelation puts Reach ahead of all other MGS-published games, including all the Halos, Fables, Gears of Wars and Forzas ever released.
"Halo: Reach is the biggest game Microsoft has ever released, and its launch has already surpassed every game, movie and entertainment launch this year," said Spencer.
"Every major instalment has grown in scope and popularity, firmly cementing the Halo franchise as one of the most popular entertainment properties in the world over the past decade."
Spencer's comments mean Reach is "bigger" than Halo 3, which broke sales records on its September 2007 release.
Of course other games have had better day one sales, including Activision's Modern Warfare 2 and Rockstar's Grand Theft Auto 4. But they were available for both the Xbox 360 and the PlayStation 3.
Last week Microsoft told Eurogamer that Halo: Reach would outsell sure to be mega shooter Call of Duty: Black Ops, due out later this year.
To date, more than 34 million copies of Halo games have been sold worldwide, driving more than 3.3 billion hours of gameplay by people connected to Xbox Live.
Read our verdict over at Eurogamer's Halo: Reach review.