Those thinking the Halo franchise has become a bit long in the tooth now have little ammunition for their argument. That's because Microsoft recently revealed that Halo 5: Guardians has become the fastest-selling Halo game of all-time.

Microsoft said the title raked in more than $400 million in global game and hardware sales in its first week, pushing the franchise past the $5 billion milestone. In comparison, Halo 4 generated just $300 million in its first seven days on shelves back in 2012.

The launch was also the biggest for an Xbox One game thus far, earning a Guinness World Record for the most watched video game launch broadcast in the process. Microsoft said more than 330,000 uniques tuned in for the event. Halo fans have logged more than 21 million hours of gameplay in the first week, 12 million hours of which were in campaign mode.

Xbox chief Phil Spencer said the success of Halo 5: Guardians is a testament to the innovative work from the entire team at 343 Industries to bring this installment to Xbox One and the incredible community of fans who have come to love the story, characters and gameplay central to the franchise.

Halo: Combat Evolved debuted on November 15, 2001, as a launch title alongside the original Xbox. Since that time, we've seen the release of nearly a dozen additional games and spin-offs in the franchise.