Too Long; Didn't Read
Nearly all Halo games follow a specific timeline detailing humanity's struggle against the alien Covenant. The Halo series occurs throughout these years:
Year 2531
Halo Wars
Year 2552
Halo: Reach
Halo: Combat Evolved
Halo: Fireteam Raven
Halo 2
Halo 3: ODST
Year 2552-2553
Halo 3
Year 2554
Halo: Spartan Assault
Year 2557
Halo 4
Year 2552-2557
Halo: Spartan Strike
Year 2558
Halo 5: Guardians
Year 2559
Halo Wars 2
Year 2560
Halo Infinite
Movies and novels populate this timeline even more densely. One can only wonder where the series will be taken from here, along with just how far each game's influence will reach.