Grand Ages: Medieval

As a player you can found new towns via settlers. Settlers can be built/recruited in the inn then be commanded to roam freely over your empire and when you find a suitable location, you can select the castle icon and a new town is founded. Note you need a builder to connect your new city with a road to provide it with building material. You can get this trophy during the campaign or a sandbox game on and or offline. During the campaign you will build some new towns, I personally didn't make it to 12 during the campaign but did during my sandbox game.