I was inspired by the Office Block Chess idea into
this. It is, essentially, Mortal Engines on a smaller scale.
Think of, instead of cities, housing blocks, which would
wander around and try to capture each other. Whenever
captures another, it would become larger. To ensure
some might adopt the tactic of building daughter
sending them on their way.
*shrugs* It's a way of spicing up dormitory towns, which
quite boring at the moment. I imagine it would evolve
steady state, where the rate of house creation equals
rate that they're being absorbed.
Later, some might want to split off on their own,
starting the Traction revolution and ending the reign of
the Mossies. That would, of course, be the goal.