Thanks for playing!
Unfortunately you missed the main mechanic of the game, which is that you can drag buildings of the same type into each other to merge them into a higher tier. This reduces the number of buildings, but accelerates the sprawl.
The goal is to get as many high tier buildings as you can without the city reaching the edge of the grid.
In any case, you looked like you had fun watching the game on autopilot, which is exactly what zen mode is for :D . Thanks again!