All details about battle and upgrade will be published after the first stage launches and before the second stage starts.
Each city-state can take the initiative to launch 10 city-state wars and be attacked 10 times a week. If the battle is successful, you can get 1.5% of the other party's revenue this week, and if you fail, you can compensate the other party with 1.5% of our revenue this week.
The initial state of a city-state is a small city-state. When certain conditions are met, it can be upgraded to a medium city-state and a large city-state. The income of each city-state will be distributed according to its proportion of city-state productivity.