OpenTTD is a business simulation game in which players try to earn money by transporting passengers, minerals and goods via road, rail, water and air.

OpenTTD duplicates most features of Transport Tycoon Deluxe and has many additions, including a range of map sizes, support for many languages, custom (user-made) artificial intelligence (AI), downloadable customisations, ports for several widely used operating systems, and a more user-friendly interface.

[6][7] OpenTTD also supports local area network (LAN) and Internet multiplayer, co-operative and competitive, for up to 255 players.

[11] The development of OpenTTD was driven by the desire to extend the abilities of Transport Tycoon Deluxe to support user-made additions to the graphics and gameplay, as well as the desires of users to play the game on more modern operating systems and alternative computer architectures which the original game (released in 1994 for DOS and programmed in assembly language) did not support.

It was created in 1996 by the FISH technology group, but Nola released in 1999 as part of a compilation of older Tycoon games.

TTDPatch, initially created by Josef Drexler in 1996–97 and still being developed in 2010, changes the behaviour of Transport Tycoon Deluxe as it is running, to introduce many new features to the game, such as new graphics, vehicles, industries, etc.

Every time a vehicle makes a delivery of some cargo, players receive an income, allowing them to build more infrastructure (rails, stations, etc.

The default game runs from 1950 to 2050, during which a player aims to get as high a performance rating (based on number of vehicles, income, amount of cargo delivered, etc.)

The amount of cargo supplied by a town or industry depends on the quality of transport players provide to move its goods.

The only infrastructure present on the map at the start of the game are roads within towns (as well as seas and rivers which ships can utilise).

The game is also home to an active modding community, with community-made additions including new vehicles, trains and scenarios.

[22] OpenTTD has been praised for the number of improvements it has made to the original Transport Tycoon Deluxe, such as the AI, graphics, sounds, and ability to play multiplayer.