+1
need lots of coal though
If there are other cities, we'll have a massive trading empire based on minerals.
Then we'll tunnel under cities we don't like and attack.
Buying ham for diamonds!
We need a set of rules we'll follow if we have a multi-city blocklander multi-indev. To keep away the chaos.
Stuff like
-Random attacking of other cities will result in a kick, attacks must be an organized effort (it can be a surprise, just, the entire city that's attacking the enemy city should be in on it, not just some rouge diamond plated moron)
-Territory rulings, max distance from another city, etc.
Also we'll have a massive feast hall and a banking operation.
And we of the underground city have open arms to our floating city comrades.