Classic Resourcemanaging and cityclusterbuilding !
In Anno, you take care over a small island (within an array of islands) building housing and workplaces for your citizens. It is a classic strategy game. The placement of your buildings is important, so is the balance between selling and buying. The problems you are facing are scarcity of resources with different islands being suited for different resources (such as spice, tobacco etc.), competitors and pirates, which are the most annoying aspect of the game.
There are loads of campaigns and scenarios coming with the game and many more can be downloaded online just in case the open-ended game is not enough for you.