18XX

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.

As a general rule 18XX titles are multiplayer board games without random variables, although there are exceptions (1860, 1870, and 18NEB can be played with two players, and 1846 and 2038 include random setup factors).

Common features
18XX games vary, but most follow this general pattern:
 * The objective is to enhance personal wealth, not the assets of any companies a player may be operating. Personal wealth consists of cash, company stock (which increases wealth both by receiving dividends and by capital appreciation), and other investments (such as private companies).
 * Players don't directly interact with the game board, but do so indirectly through companies they control. Generally, the player who owns the most stock of a company is the president of that company and makes all decisions on behalf of that company. Usually, the president is also required to help fund the company when it lacks sufficient funds to pay a required expenditure (such as a train).
 * Game play alternates between "stock rounds" and one or more "operating rounds". In a stock round, players buy and sell stock (some games have company actions during a stock round as well), while in an operating round players take actions on behalf of companies they control, including laying track, placing station tokens, operating trains, withholding income or paying dividends, and buying trains.
 * "Certificate limit": there is usually a limit to how many corporate shares and private companies a player may own, to keep the game competitive by preventing snowball effects resulting from early leads by some players.
 * The "President's certificate" (or "Director's certificate") represents control of a railroad corporation, usually represents a greater percentage of corporate stock than other certificates (e.g., 20% as opposed to 10%), and is usually the first one purchased for a company (with its purchaser setting the price, or "par value", for regular shares of stock in many titles in the series). If another player accumulates more shares in a company that the current president, he acquires the President's certificate (with attendant side-effects for both players regarding certificate limits) in exchange for his own lesser shares, and becomes the new controller of the corporation.
 * Certain games may impose restrictions on the order in which companies may be started (generally to impose a historical context upon the game), and they vary in how many shares must be purchased before the company may operate ("floats").
 * The map is usually a hex grid that depicts cities and terrain features. Hexagonal "track" tiles (representing available land-rights) are laid on top of this map to represent the growth of railroad networks, and tokens are placed on the board to represent stations (as well as special abilities from private companies). Cities have values which can vary based on which tiles have been laid on the city, the phase of the game, or even which type of train is used to reach them. Different color tiles are available in succession, and in phases. These phases are typically determined by the first purchase of a more advanced type of train.
 * A company's stock price is adjusted based on the revenues earned and whether the president chose to pay dividends or to withhold the earnings in the company treasury. Stock prices are usually also affected by actions in the stock round, and some games have other mechanisms that affect the stock price.
 * Scarcity (forcing future-turn planning by players) of available corporations, shares thereof, train types and track tiles.
 * Trains become obsolete, and must be replaced by ever more expensive trains that also have greater capacity for earning revenue. Purchase of a new type of train usually triggers other events in the game, such as when older trains become obsolete, the availability of different sets of tiles, closure of private companies, etc.
 * Game end is usually determined when the bank runs out of money, and also by player bankruptcy (when a player cannot pay the debt of a company he controls). Some games do not end when a player goes bankrupt, while others add other conditions for ending the game such as when a stock reaches a certain value on the stock market, or the most advanced type of train has been purchased. Other games do not feature bankruptcy at all, and enable a player to place a moribund company in "receivership", or be incorporated into a government railway, and walk away from debts.

Differences
A new 18XX game is usually different in significant ways from predecessors. 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:
 * Initial Auction - there are many different ways to distribute the initial privates and corporations.
 * Private Companies - most 18XX games have private companies which are entirely owned by one player, and represent the earliest companies in the game or provide special abilities. "Privates", as they are called, generally do little other than provide revenue, but in some games they control access to hexes on the map. Some games have very similar private companies, some have very different private companies, and some dispense with having private companies at all. Some titles (e.g., 1835 and 1861) also have Minor Companies, which are again owned entirely by one player but play a more dynamic role than Privates.
 * Corporation Funding - some games have full funding for a corporation as soon as it floats, while others have the company receiving money only as each share is sold. Some games require the corporation to reach a historically relevant destination in order to receive some of its capital.
 * Company Types - some games have multiple company types. These types may vary based on how many shares are available for purchase, the funding model for the company, the number of station tokens available, or which types of trains may be purchased by the company.
 * Corporate mergers and demergers - some games feature optional, or forced, mergers or splits of one or more companies.
 * Corporate stock-ownership - some games enable companies to hold their own stock, purchase private corporations, and/or own the stock of other companies (even to the point of owning or as prelude to merger).
 * Train Types - some games may offer multiple types of trains with distinct capabilities or lifetimes.
 * Some trains may "degrade" into other train types upon certain events (for example, delayed obsolescence of 4-trains in 18MEX, or normal trains becoming H-trains in 1844).
 * Trains may become available in unusual sequences. For example, in 1830, diesel engines are available as soon as the first 6-train is purchased &mdash; all the 6-trains are not required to be purchased first.  In 1824, G-train availability is controlled by when normal trains are purchased.
 * Certain trains may be restricted in terms of which locations they may run to or may count revenue from, or they may provide bonuses for running to certain locations. For example, in 1844, H-trains are prohibited from running to off-board locations.  In 1854, only Orient Express trains may run to certain off-board areas.  In 1889, diesels get special bonuses for off-board locations.  In 1826, E-trains and TGVs ignore dot-towns.  TGVs in 1826 and 4D-trains in 18MEX double the value of cities they count.  In 1824, only G-trains may run to mines and the corporation always gets the value of the mine rather than it being potentially paid to stockholders.
 * Theme - a few titles eschew the common railroad/stock-market theme. For example, 2038 involves space exploration of the asteroid belt, while Ur, 1830 BC involves building dams and canals in ancient Mesopotamia (in the latter game, "corporations", "presidents" and stock "shares" are represented by kingdoms, rulers and parcels of land).

Conventions and Tournaments
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.