Simutrans is a transport and economic simulation game. Simutrans has not yet reached production state, but it is quite possible to build big transport networks between the industries and cities.
The player can create bus and rail connections and transport passengers, mail and goods in and between cities and industries. Even passenger ferries and oil tankers are included in the game. Goods are produced by industries from raw materials, sometimes over many steps of intermediate products, i.e. coal and iron ore are needed to produce steel in a steel mill. Oil may be transformed to plastics in a refinery. Plastics and steel are used to build cars by the car industry. Finally the cars are sold in the cities. Now they need gas to run, which also will be produced at the refinery.
All goods need to be transported. This is the players task. Transport the goods and let the industry live up. But be careful not to destroy your environments.
This very well made game will have a very special appeal for fans of SimCity and Transport Tycoon.