With a picture like that im surprised you not saying Make 343 great again.
Imagine your a lone odst who’s pod landed in the snowy mountains of zeta Halo. You have to find safety avoiding the banished patrols and well the environment.
I would like to see Halo 5 again. Make a spon off game based on the HCS settings
An insurrection focused game could be interesting if done well or even a more story focused game in the same vein as the Kilo-Five trilogy could be great.
A game focused on the Rebels fighting against the UNSC.
Each individual boss can be a Spartan 2 hunting you down. The boss fights would vary by each Spartan having a different piece of equipment or armor ability from one another.