>>532447538
>galaxy-wide
everything's irrelevant, too small for any detail, planets conquered after 20 minutes fighting in one map would be deeply unsatisfying in the long run. Space battles guaranteed to have to be made here and they'd probably be all of your "field battles" with making planetfall just being a siege battle.
>sector
could work, maybe like ~20 planets with 2 to 4 regions, maybe only one region per planet has some kind of space access allowing you to have some kind of defensive strategy possible, but it'd be esoteric and confusing, campaign would probably have to be so digital there wouldn't be enough granularity as to how you march/fly an army around, would have to maneuver like DoW.
>one planet
would be kino, could have lots of depth, but they can't possibly fit the grand scale of the setting here, and that'd make 40kiddies cry, there'd probably be some fucktarded mcguffin story hook that CA would invest too much time in to the detriment of everything else. Playing tyrannids or druchii here wouldn't really capture the whole fantasy of demolishing planets or raiding across the stars.