In the game, when you first open the Civics page you will see 25 options divided into 5 categories. The categories are: government, legal, labor, economy, and religion. Initially, you will be limited to the lowest levels for each (making you a barbaric, decentralized despotism with tribal labor and practicing paganism), but you will unlock more of the choices based on your research. Changing to new Civic forms will have a dramatic effect on the character and success of your civilization. You'll be able to boost or cut productivity, wealth, and happiness, make choices to increase/decrease the spread of religion, and even affect your ability to produce and maintain a large standing army.

So, the choice is up to you. Will you be a despot or a king? Will your people respond better to a democratically elected ruler or a theocrat? Will you have a free market or is everything state property? Make the best choices and lead your people to their rightful place in history!