Halo Infinite's multiplayer on Steam has seen a significant drop in player base, losing around 98% since its launch. Concerns arise about the game's future, but it remains free-to-play with updates.
Not surprised, it doesn't really feel like a halo game. Single player was sort of fun, but not worth replaying. Halo hasn't felt like halo since the original team left, so I'd call it generic fps at this point.
Halo master chief collection is what you want. It has all the campaigns for 1-4 + reach & odst, they also remastered the older ones. When you play them all back to back you can really see the drop at halo 4, which was the first non Bungie game.