There are several forms of government with which you can rule your civilization, but none offers complete control. The standard forms of government are: Despotism, Monarchy, Communism, Republic and Democracy.
Under autocratic regimes (Despotism, Monarchy and Communism) your citizens readily support the military, as military units stationed in a city can prevent unhappiness by enforcing order, but reduce your trade income through corruption. When granted representative government (Republic and Democracy) they are efficient and productive, but demonstrate against the use of military force by becoming unhappy, the only effect is negative — citizens become unhappy when their city is supporting military units which have been deployed into an aggressive stance.
Land units are loading into transport vessels, so that could transportable between islands and continents in ships: Trireme, Caravel, Galleon, Frigate, Transport, Submarine and Carrier. This feature needs to the new land generation method which will be create continents and islands on the map.
Besides working terrain gifted with rare commodities, or with access to waterways and roads, you can increase trade by establishing trade routes between cities. You accomplish this by producing a caravan or freight, sending them to another city at least eight squares away or belonging to a different civilization, and giving them the make trade route command.
The origin civilization of the unit gains immediate revenue in gold and science from selling its trade goods at the destination city. The initial revenue depends on the trade already produced by the two cities involved and their distance apart.
Also, an ongoing trade route is established that benefits both its origin and destination equally by generating trade points for each city every hour. The amount of ongoing trade is based on (but not equal to) the sum of trade points from the tiles worked by the two cities; it is doubled if the cities are on different continents, and doubled again if the cities are from different civilizations.
The number of trade routes per city is limited to four. If you attempt to establish more routes, the trade route with the smallest ongoing revenue is lost if it would be less than the new route.
Turns a city into settlers: Make a disband button that turns a city into settlers, so that the occupied cities could convert into settlers.