It was very popular because the game had no end. A player could not win or lose. This was the start of all simulation games.
At the start, the player has to build power plants. Power plants make power so the city can have electricity. By building power lines, power is connected to the different areas of the city. Water needs to be pumped in from a river using pipes to connect them to the city.
Smaller areas are marked out. These are made either residential, commercial, or industrial zones. Zones are the only places where buildings can develop. Every city needs the right amount of each zone otherwise the city will not grow.
Roads, schools and hospitals must all be built for the city to get better. Parks and libraries make more people want to move to the city. Railways and highways provide ways to connect to other neighborhoods.