I found an example mechanic.
In Victoria 2 there is map and you move units and these fight, standard so far. But, it's not the core activity, actually, those military units are not that important most of the time. Majority of the "action" is in the "influence" mechanic. You have influence points, you can spend these on various minor nations. Then, when you accumulate enough points in a nation you have one of 4 actions available:
* increase your relations with that country
* "take over", to be more precise "include in your sphere of influence", you can do it only if you have the highest relation level
* reset all influence points of another major power (so they can't increase relation or put that country into their sphere)
* "poison" target major power's status (temporarily) reducing the speed of acquiring influence points in that nation
In practice the player spends most of the time watching these parmaterers and making diplomatic actions while military actions are rare.
From my prespective, the military units could be removed from that game (and replaced with some more abstract "army" thing that simply reacts to orders like "conquer country X").