Before the Cosmic Era was it's own region on the citadel it was really brought to life under the idea of making a card type game to play in the bar while the non-nerd wives and GFs did their thing at the model horse convention. That eventually fell by the wayside, but it's crept back up again.
I see playing out battles in the Cosmic Era on a hex map, somewhere between Settlers of Catan and Battletech. Build arcos, claim ruined cities, establish resource gathering efforts, transportation grids, etc while developing and deploying upgradable military style units.
Infantry, basic, advances to special forces, which advances to exotic forces like SOLDIER from FF7, parapsychic martial artists, bullet bending gun adepts, etc
Power Armor Infantry, somewhere between Starcraft, Battletech and Warhammer
Units are bought and deployed like a RTS game, but with diplomatic options, hacking and cyber warfare and all that business.
MegaCorp Sabotage: all units cost X% more for the next 1D6 turns