Fallout style
ju start as a murine and lvl (maby 30 lvl's) up till you are spartan or higher and fight vareus covenants, wildlife, bad UNSC that belives on the prophet, maby not ot large like "Over 10 000 square KM of free roam-able world overall" and stuff that remindes of halo, halo world (forunner strukture),weapon,armor,+ meele weapon
(if larger world vehicles enabled)
fully costumasing armor,weapon, player(face,boddy,sex)
mian Quest line + side Quests, NOT ONLY random side Quests
it kan take place any time but probebly at the end of halo 6 ore between halo 3-4 it can be master scheif living a rpg
+ no wats or like it thats fallout style
WOW style
ju start chosing side Covenant or UNSC then race if UNSC ,murine,spartan,ODST.. if Covenant ,elite,brute,grunt
and every race have different classes, skills
fully costomasion over armor,player(face,boddy,sex)
kinda a main Quest many side quests the end of man Quest can bee each oter of team fight pillar of atumn or supercarrier or a common enemy like prophet
a halo planet the ring or onyx ore somthing else
it can take part between halo2-3 bekouse the covs and unsc are kinad friends but still enemys
moundts and pets.
a litle about my thoughts