You know for a while now I have been considering the elements of war we often don't represent in games, such as fog of war and recon, and the way off table assets such as artillery and air-strikes interact with this. Hacking and digital warfare is another one that is sadly under-represented in my opinion.
Naturally people will be able to point out some games that do these things right, tough netrunning might be the exception.
In any case what I'm saying is I like the notion of a side game, potentially a card or tile based game even, that simulates these elements in a interesting manner and influences the "main" battle in significant and interesting ways.