Banished is this incredible city-building/management game that I picked up during the Steam summer sale.
It is quite difficult--especially on hard with disasters turned on. You have to manage your citizens through different professions divided between food production (through farming, animal husbandry, gathering, fishing, and orchards), craftsman (blacksmiths and tailors to provide tools and clothing), and more resource gathering type jobs such as foresters and miners. Later on, you can get more infrastructure relates professions such as traders, market vendors, physicians, and teachers. You require not only enough food to feed your people, but also sufficient variety to promote good health. If you don't prepare for winter with enough firewood, your citizens freeze to death because they can't heat their homes. Although the graphics aren't incredible, I find something very charming about them. The maps in this game are HUGE, and with careful planning and management, you can eventually fill them out.
You also have to manage population growth by determining when to build houses and/or accept nomads into your lands. If you stop building new houses, young people will not marry and have children and eventually your whole population will die off. If you build too many houses at once, you will have a huge amount of children that you have to feed even though they can't work--and then your people will die of starvation.
One of the best things about this game is how it leaves progression up to you. Any building can be built at any time provided you have the resources and labor.
The details in this game are incredible: down the point where you can't keep planting the same crop in the same field or the nutrients in the soil will be depleted--necessitating the practice of crop rotation.