I would play the heck out of thatHeh. One massive city. You start on the edge. You have to work your way to the center, to the Tower of Evil,
fight your way in to the final control room. (said tower has all sloping sides, so forget landing a 'copter on it)
Final building is like Dishong on steroids, espresso and pixiestix.
Biomes change as you work your way inwards...
That could be an interesting one... (most likely would have to be a mod)