I would make a "two sided tower defence game", where you would control the logistical flow to different bases. When they are well supplied they can pump out unit waves, which can defeat the enemy. The enemy would do the same thing. The player would have to balance the flows through the network. The tool for doing so would be some settings in each node and "vertice" that connects it to other nodes. Resources move out of base back to home-base, while units and troops move away. Dont know if this makes any sense. The player would play it by manipulating what is produced in the main-base, and then manipulate what and how much units should go where. The numbers indicate how many units are "fortifying" the node.

Uhh... my language has degraded... to much sc2 :S