I've been throwing out a lot of algorithms, data tables, and hair-brained ideas that end in a question mark. So I'm taking this blog to spell out what The Epic of Gilgamesh will be like to play.
Your character is a Demigod, born in an obscure (and completely made up) lesser city in ancient Mesopotamia. Your father was the local patron god. Your mother... not so much. When you reach the age of majority your father makes an appearance, declares you ruler of the village, wishes you the best, and then poof zaps away in a puff of smoke.
You start the game in control of a small city. Everything they have is yours to command. It's just not all that much. Some fields. Some traditions. A temple. A market. No army to speak of, nor fortifications to defend it. Just the crops you can grow and the silver you can make from selling it.
Because you are the Child of the local God, you have the Village's undying loyalty. This little city will always be home. Unless you manage to piss off someone enough that they come around and burn the place to the ground, and put all of its people to the sword. Because, being the Bronze age, stuff like that happens.
The first part of the game will be trying to expand the trade in your city. Or... maybe, figuring out how to invade nearby cities. As silver starts flowing in, the next part of the game will be defending your city from invaders. As other states (and their patron Gods) view you as competition, you also may find yourself locked in a war of the Gods, or holding back the Imperial ambitions of a rival.
All the while you have one eye on the goal of living forever. You will also be getting crazy requests from the Gods that have to be obeyed or... well... bad things will happen to you and/or your citizens.
You will be given an interface to control life in the city:
Throughout the game you will be interacting with AIs that are playing the same role in the game as you. They are running their own cities, with their own goals. Some can be bargained with. Some can be cowed. Others are just plain assholes. Cooperate with those you can cooperate with. Compete against those who want a competition. And wipe out out those that can't be reasoned with.
The computer will be performing complex models in the background of crop yields, warehouse spoilage, construction, epidemics, transportation, population growth, population contentment, spiritual influence, and more. You won't be interfacing with those models much. You will have advisors who will carry out your orders, and make helpful recommendations of what those orders should be.
When you go adventuring, it will be with a party. Before you leave, you pick the composition of that party. How many warriors. How many wise men. How many wagons of supplies. What battle tactics to utilize. Combat itself uses a custom built D&D style engine. You will be able to input moves for your characters, with orders to your subordinates in a turn by turn fashion. Or you can just set the automation loose, and get back an after action report. Your party members will be able to fight with or without your orders to do so, their success determined by skill, equipment, health, and initiative.
Here is a quick rundown on the types of advisors that you are going to need to run a small kingdom:
Each of the ministers will have a list of priorities or projects they would like to achieve, as well the budget required to make those priorities or projects happen. Different individuals may have different interpretations about what their job entails, and how best to carry out those duties. Which is why it is important to interview your Masters before you set them loose.
Essentially, the game could just play itself. How deep down into the details you as the player want to be involved with is a matter of taste. You are there to make high level decisions. That's it. Kind of like real royalty. But unlike, say, Fallout 4 and it's settlement system you won't be bothered with pesky messages to come rescue City Z. They'll just be a smoking ruin when you get back. (But that's not the end of the game, you can always go off and found/schmooze/invade/etc your way into a new city.)