From the website:
In "Cities" you are the architect of a city of the world. You try to build a city that is most attractive for tourists. You position attractions close together. You build parks as big as possible and place terraces close to the water. You guide tourists to their favourite spots, because only through them you can earn your points.
But... you never know exactly which tile will be drawn next. Will you wait another round for the perfect tile? Will you adjust your planning? Or have you got a brilliant idea and can you position the tile in a way that it brings points for more than tourist?
Every player builds his own city and makes his own choices. "All" you have to do is make better choices than your opponents!