The Nomad unit should have several qualities : - Has properties of a city including Population, Food and Production. (Like a virtual city.) - Appearance and costs similar to a Settler unit. (Maybe a Horse-Settler for Steppe-Tribes like Mongolia.) - Can move on the map and found settlement/city. - Can partially harvest Features and Bonus Ressources (like a worker) to get Food and Production. (Harvesting gives a smaller yield and does not remove the Feature/Ressource but disables it for some turns.) - Can produce basic units (including new Nomads) by using Food and Production. - Instead of Population Growth, a new Nomad is created.