I like playing my Civ games with themes for the world, like for example only Native American civs or only African civs. While choosing what civs to put on a map is built-in to the game already, there is no way to choose city states other than altering the game files.
So here's a mod that let's you control what city states the game will load, and it is hopefully easier than editing the originial game files. The mod folder contains an XML file that deletes all city-states from the game. A provided readme, found in the mod folder but also in the spoiler below, tells you how to choose what city-states the game should not delete - and these will be your chosen city-states.
This way you can easily play a game that has not only just specific civs but also specific city-states. I hope someone will enjoy this.
This mod is made for BNW expansion.
Readme on how to use the mod:
Simply extract the CityStateSelection.zip file and move the City State Selection (v1) folder to My Documents/My Games/Sid Meier's Civilization V/MODS
[BNW] City State Selection 2016-10-05
[BNW] City State Selection