18Ruhr is a railway game in the 18xx series, in which players buy and sell shares in railway companies. The companies earn money for their shareholders by laying track, building stations, and running trains. The special feature of 18Ruhr compared to other 18xx games are the coal mines and steel mills, which are independent companies with their own shares. There are interdependencies between the railway companies and the mines and mills which reflect the development of the Ruhr during the 19th century.