Call of Duty: Modern Warfare II crossed the $1 billion mark in sales in just 10 days. That’s the fastest title to reach that milestone in the franchise’s history, says Activision-Blizzard.

To date, fans have played more than 200 million hours of the game and battled in more than 1 billion matches on consoles and PC.

While hitting $1 billion in sales in that span of time is impressive, it’s not an industry record. That honor goes to Grand Theft Auto V, which topped $1 billion within three days of its 2013 release. Still, it’s a big reassurance for both Activision and Microsoft, which is hoping to acquire the publisher. It’s also the biggest opening of any form in the entertainment industry this year.

Call of Duty is traditionally the industry’s best-selling game each year, but there have been quiet concerns about the franchise in recent years as sales fell short of expectations.

Modern Warfare II is a sequel to 2019’s reboot of Modern Warfare, featuring iconic characters and themes from the original series, but packaged into fresh stories set in today’s world. The single-player campaign has received so-so reviews, but the multiplayer has been highly praised.

The success of the game is certain to be noted by regulators who are deciding whether to oppose Microsoft’s $68.7 billion planned acquisition of Activision-Blizzard. The deal has been under especially close scrutiny in the U.K. as regulators there fear the merger could harm competition in the video game industry, especially if Microsoft at some point no longer publishes Call of Duty games on Sony’s PlayStation or other platforms.

Xbox chief Phil Spencer has said Microsoft has no plans to take the franchise away from PlayStation.