18XX is the generic term for a series of board games that, with a few exceptions, recreate the building of railroad corporations during the 19th century; individual games within the series use particular years in the 19th century as their title (usually the date of the start of railway development in the area of the world they cover), or "18" plus a two-letter geographical designator (such as 18EU for a game set in the European Union). The games 2038, set in the future, and Poseidon and Ur, 1830 BC, both set in ancient history, are also regarded as 18XX titles as their game mechanics and titling nomenclature are similar despite variance from the common railroad/stock-market theme.
The 18XX series has its origins in the game 1829, first produced by Francis Tresham in the mid-1970s. 1829 was chosen as it was the year of the Rainhill Trials. 1830 was produced by Avalon Hill in 1986, and was the first game of the series widely available in the United States; it is seen as the basic 18XX game by the U.S. audience.
In addition to traditionally published games, the 18XX series has spawned self-published variants and games published by low-volume game companies.
With few exceptions (such as 2038), 18XX titles are multiplayer board games without random variables in their game mechanics.
18XX games vary, but most follow this general pattern:
While adhering to common similarities (see preceding section), each 18XX game differs from the others in subtle or significant ways in rule set as well as game map. As with games in general, each individual mechanic has probably been used before, but a new game can put together a set of mechanics which provide a new and interesting challenge. Some typical areas of difference are:
A number of conventions have at least some emphasis on 18XX games, including the Chattanooga Rail Gaming Challenge, held in January or February in Chattanooga, Tennessee and run by Mark Derrick. 18XX games also figure prominently in various "RailCon" and "Puffing Billy" tournaments at many conventions.