Banished is the best city builder I've ever played (and I've played a lot, having been a fan of the genre since the original Sim City and the old Sierra historical builder games). The game is deceptively simple, you start with a few settlers and minimal supplies and you build a thriving settlement. Sounds easy enough, but it's probably one of the most challenging games I've played.
There are a variety of crops, animals, and natural resources. Your setttlers will plant and gather and use these to build a rustic town. Steel tools and stone houses represent the pinnacle of your settlement's technological advancement. You can barter goods with a few visiting tradesmen and some nomads may periodically ask to join your settlement, but that's the limit of your outside contact. Peace reigns, you won't need any military (or even police) here. The only hostile forces you will encounter in Banished are tornadoes, fires, diseases, starvation, and cold. And you will encounter them, a lot.
Although the game is relaxing to play, it can at times be incredibly difficult. Your settlement might be going along nicely for 100 years, with plenty of food and lots of citizens available to fill all the jobs that need to be done, and suddenly everyone has cholera and you're closing down the schoolhouse to free up some child laborers to expand your cemetary. Banished is brutal that way. But it's also beautiful. The music and graphics and effects are really appealing, and the immersion factor is high. It's definitely one of those games you can sit down to in the early afternoon and play for hours and hours and then be surprised to find your stomach growling and oh hey when did it get so dark outside?
The developer is very active and involved in the community, and new features are added often. Now the game offers modding capability and Steam Workshop. So far the community has responded with some amazing tweaks and additions which only make the game even better (also a little easier, if you find the challenge a bit much).
I can't wait to see how Banished continues to evolve, which it seems to do in much the same way that my tiny settlements grow and evolve, with all of the little details coming together to make something really satisfying and enjoyable.