Production is necessary to produce units, buildings and wonders. Units and some buildings are required production points to keep them up. The level of production is formed by the quality of land and natural goods.
Food resources are dependent on the land the city is built on. The food is a necessity to support the citizens. If food is not enough the granary decreases. If granary is empty, the citizens starve and the population is reduced.
Trade points are reflection of how strong economically a city is. Trade is achieved through external commerce with other cities and is positively influenced by forming trade paths and routes using caravans. Trade points are distributed as taxes (converted to gold), Science and Luxury. Some of the buildings increase the efficiency of trade: palace, courthouse, highways
Gold can be used to buy units or buildings. It is produced from the taxes collected from trade. The quantity of gold may be important in times of war as a way to quickly acquire units. Treasury is a national asset.
Happiness keeps the city order. Unhappy citizens may destabilize the city production and trade and may make it easy to revolt
Luxury influences the spirit for work and the happiness of the workers. It is applied locally for every city.
Corruption decreases trade points. The level of corruption is influenced by the government type and the distance between a city and the capital.
Depending on the type of government some units may require more food to survive. Types of government influences the level of corruption and may impose limitations on taxes
Taxes level influences the amount of collected gold in the treasury. Tax level may affect the happiness of citizens.
Citizens demand food to survive and grow population. This is achieved by storing food in the granary. Granary increases or shrinks depending on the delivered resources. Some of the units require food points to keep them up.
Land is divided in tiles. Each tile represents a different type of surface and may indicate the presence of goods. Land can be manipulated by citizens. Each tile has food, production and mobility characteristics. Land tiles type also affects defense.
Technological development decides for the strength of the civilization in aspects weapons and effectiveness of production and trade. Technology enables and unlocks military units, buildings, wonders and types of government.