Xbox Wire discusses the recent release of the Windows edition of Halo: Reach in Halo: The Master Chief Collection. They're making a note here, huge success, calling it a blockbuster launch:

The long-awaited debut of Halo: The Master Chief Collection (MCC) on PC was worth the wait, thanks to the amazing Halo community as well as a host of all-new players experiencing the Halo universe for the very first time. The release of Halo: Reach in MCC on both PC and Xbox One on December 3 led to a monumental launch for the Halo franchise, with record numbers including:

• Nearly 3 million players of MCC on PC and Xbox One during launch week
• #1 top-selling game on Steam during launch week and the highest-ranking debut for an Xbox Game Studios title on Steam
• #1 most-watched game on Twitch during launch day

When fans haven’t been playing MCC, they’ve been watching, viewing nearly 3 million hours of Halo streams during launch week, pushing MCC into the #1 most-watched position on Twitch during launch day.

PC players and media have taken notice of Halo’s return on PC, with MCC rated “Very Positive” across more than 35k Steam Customer Reviews and The Washington Post proclaiming MCC on PC as, “the best deal in gaming.”