Update: It's live.
Over the past 24 hours, multiple Twitter accounts claimed that Halo Infinite's free-to-play multiplayer will launch on Monday, November 15, nearly a month before the planned release date on December 8. November 15 marks the 20th anniversary of Halo: Combat Evolved's release alongside the original Xbox.
The initial tweets were coy and unsubstantiated, but picked up steam when YouTuber Nate the Hate tweeted "I can independently confirm & share with you today that Halo Infinite multiplayer will be made available on Monday, November 15." Again, there's no source to go on, but a line of code from the Xbox store which cited a November 15 "PreOrderReleaseDate" added to the excitement. The date is paired with a timecode for 6:00 pm, the same time in GMT that Microsoft is starting its Xbox Anniversary Celebration.
A final piece of confusing "evidence" circulating is Google displaying a countdown announcing Infinite's release date Monday, but it seems unlikely this would be based on insider information—Google result pages will often pull out and highlight inaccurate text.
According to HaloHub.gg, Infinite's multiplayer servers are now accessible, and the first listed "Fracture" event is due to start on November 23rd, while Season 1 Heroes of Reach begins on November 15th.
The best evidence that Infinite is coming on Monday rests with Microsoft: After hours of speculation, no one at 343 Industries has shot the rumor down. Microsoft PR has not responded to PC Gamer's request for comment. Meanwhile, Microsoft's social media team has either accidentally or intentionally broken the official Xbox twitter account. We're either about to experience a rogue Cortana takeover, or it's a very strange Friday in Xbox land.
As of 4 pm PST, this is what halo.xbox.com looks like:
I'll update this post with more information when I have it.