A pretty fun game that lets you basically create infinite little worlds within in each level, of four different types depending on which level it is. I particularly love the look of the deserty one and all the different mountains towns and special builds mean you can put effort into making the landscape look nice. There are often slightly too many corner pieces to connect two biomes then squares that are whole biomes but you can work around it.
There are also a lot of ads but i have found that you can just play it offline and they won't play and it usually functions pretty well.