Every time the years progress, double the population of each country. The amount of army can't be greater than population. If you don't have a nation: Then find unclaimed land and claim it. Each country starts with 12 population and no army. If there isn't any unclaimed land: Then rebel any country. But the country you rebelled can't have more than 100 population and 40 army. Don't make your country too big. If the rebels win: Then claim 1/3 of the country. You can't rebel if there is less that 5 countries.
New thing: Gulfs. A gulf has a 1/3 chance to spawn when a new country is present. (Only Sube13579 can edit oceans, lakes, seas and gulfs)
