If you had the resources and legal team what type of system would you use to make this happen?
It'd end up looking something like the Infinity RPG or Only War.
Either small teams of specialists with unique capabilities undertaking dangerous missions, with hints of divided loyalties or other agendas to spice things up, or a broader and grittier war scenario of grunts in the firing line of a conflict far larger than they could possibly understand.
The former seems more fun, personally, but I know a lot of people love the latter style of thing.