At one point my beta group had exhibited some interest in, at high tiers, being able to use production from multiple cities to build a Titan Construct of sorts, like the spaceship victory but instead of a spaceship, building a giant walking steam titan that kills all your enemies.
But that doesn't really feel Dural-ish. Now, when I drag the Mechanos in.......
hmmm mechanos...
National Units Limited to 1 - Can rebuild parts if they get intercepted
Titan Head
Titan Torso
Titan Left Arm
Titan Right Arm
Titan Pelvis
Titan Left Leg
Titan Right Leg
(could add feet and hands too)
Titan Power Plant
All 0/1 units, movement 1 except Power plant, it is immobile, have to move other pieces to it. Varying costs and Resource requirements. (Might consider adding some of the new resources from Orbis also)
Once all in one city combine them into the end result. Which is a World Unit, can only make one.