18GB is a member of the 18xx family of games, set in Great Britain. Players invest in railway companies, which build routes and run trains, with the aim of ending the richest player. 18GB combines elements of 1825 and 1860 on the one hand with features of 1830 and its descendants on the other hand. When setting up the game, the railway companies are randomly grouped into two tiers, so each play will see the map develop differently. Players may buy up to 100% of ten-share companies and may sell any number of shares into the open market, even including the directors' certificate. Each share sold depresses the stock price of that company, but the stock price will recover several places if the company's income is double, triple, or four times its stock price. The number of railway companies scales with the number of players. The two 2-player scenarios play quickly, while the game becomes longer and more complex with more players. 18GB has an unusual mix of city tiles and associated rules for upgrading them, which makes the engineering side of the game more challenging than many in the 18xx family.