I would love to see all invasions mode, with a “unhistorical day” once a week, in reverse or with allies defending and axis attacking.
For example : Beachattack:
→ normal USA fights its way vs Germany as it used to be 6 days a week
→ reverse Germany fights the US back to the beach (USA simply defending)
→ inverse USA defending the beach and Germany tries to take it.
It would bring some spice into the game and by limiting it to one day the main historical fact stays the same.
Pros :
more diversity in gameplay single nation player get to know the tactics of the opposing nation better.
balance issues could be detected with more ease. (f.e. if us stomps in attacking AND defending it clearly is a performance issue of skill or gear)