Elemental is set in an mediaval setting. What really is important about that setting is the vassal system of nobles. Sovereings give there land away to nobles so that they gain benefits from these.
My suggestion is introducing an nobles system. In short: you would give land away to noble famillies so that you can get different bonusses, short or long term. Seeing that this is not an "easy" addition, but one that will take some time, this would be a post release suggestion.
These famillies could work like corporations did in Civilization: Beyond the sword. You build ambassadors or "missionaries" units that can give cityrights to an noblefamillie. There could be three types of nobles: Merchant (Civic), Warlords (Warfare) and Religious (Magic).
- Merchants could decrease taxes and improve the industrie with extra production (Give us some tax brakes and we could grow this towns industrie for shure!). Or they take a large chunck of resources and give extra taxes in return (We could make these metals into some nice trinckets for the market, and we'll give you a cut).
- Warlords could take metal but and give defense and critical-hit bonusses to trained units (. Sure some weapons and armour are lost, but the ones that surive our training are the best). Or they could decrease taxes or food, but provide a large standing militia in your city (Give us some farming land or part of your industrie and we'll certainly protect this city). Maybe Warlords can give you an strongh army in exchange for 3 grain.
- Religious could decrease research but improve growth (Don't think to much, just breed). Or they could increase mana in exchange for food and a tax redux (We would like to build an monestary here for prayers toward you kingdom/empire).
It would be awesome if all of these famillies would make a "manor" in your town visable as a structure on the map (randomly placed by a computer). These famillies could give some bonus for each city they got some controll in. Famillies could give quests for there loyalty. Maybe they could demand being married into your royal famillie which would make the bond with your sovereing final (Dynasty system).
I'm wondering what you all think about this.