I think specifically in the case of Halo, the surprise is because it was such a powerhouse of a franchise in the 2000s into early 2010s. Halo was the Fortnite and Apex Legends before Fortnite and Apex Legends in terms of player retention.
Halo 2 and 3 had thriving playerbases for years after release. Infinite came out just over 1.5 years ago and has already lost almost all of its players. The Master Chief Collection currently has more players than Infinite with 5,200 to Infinite's 3,000 on Steam.
I spent countless hours in high school playing Halo 3, and even a few years after release, you'd have hundreds of thousands of players online. Two years after release in October 2009, Halo 3 had close to 759,000 players online in the span of 24 hours, plus about 129,000 playing ODST, which had just come out a mont prior.
I'm not a fan of gaming as a service, but it clearly can be a successful business model for sustained success, so you'd think that one of the most iconic gaming franchises of all time would be able to harness that.
Agreed 100%. Halo 4 was the beginning of the end for Halo, imo. I thought Reach was fun, but I was never a big fan of the sprinting, armor classes and weapon bloom. It still felt like Halo overall, though. I remember playing Halo 4 on launch day and immediately being disappointed. I still probably put 100+ hours into it at the time, but I remember thinking it didn't truly feel like Halo — at least not like its predecessors.