The Halo franchise consists of different Halo games, started in 2001.
The best game in tier S+ is Halo: The Master Chief Collection. Halo: Combat Evolved and Halo 2 are the most prominent games in tier S. Halo: Reach is the leading game in the A+ tier; Halo 4 and Halo Infinite rank in the A tier.
The best game in tier B+ is Halo 5: Guardians. Halo 3: ODST and Halo Wars rank in B tier, while Halo Wars 2 ranks in C tier; The top games in the D tier are Halo: Spartan Strike and Halo: Spartan Assault, and halo Recruit and Halo: Fireteam Raven ranks in the F tier.
S+ Tier

Halo: The Master Chief Collection
S Tier

Halo: Combat Evolved |
Halo 2 |
Halo 3 |
A+ Tier

Halo: Reach
A Tier

Halo 4 |
Halo Infinite |
B+ Tier

Halo 5: Guardians
B Tier

Halo 3: ODST |
Halo Wars |
Halo: Combat Evolved Anniversary |
C Tier

Halo Wars 2
D Tier

Halo: Spartan Strike |
Halo: Spartan Assault |
F Tier

Halo Recruit |
Halo: Fireteam Raven |