The game interface is in full 3D, with free camera movement. The square grid is no longer rigid, as it was in Railroad Tycoon and Railroad Tycoon 2 - rail and structures can now be rotated 360 degrees.The track building function is not very realistic, as tracks are sometimes built at angles almost at 90 degrees to each other.
The economic model has been reworked. In previous games, goods could only be picked up at a station, and revenue depended on the distance between stations. Carloads in RT3 slowly move across the map (representing road and water transport) along the gradient of a scalar field representing price, where supply and demand sites function as sources and sinks. Revenue depends on the price difference between pick-up and delivery. This has several effects; raw materials can find their way to industries and get processed, without any trains involved, and a train does not need to pick up goods at the source.
Other changes include: each carload of mail, passengers and troops now has a destination; car setup can be automated, so that trains always pick up the cars that yield the most revenue; warehouse buildings also appear in the game, completing the commodity market the same way as ports do; trains can pass each other on a single track (as in RT1 on lowest difficulty level); no need for signal towers; service and maintenance depots, as well as station improvements (post offices, restaurants etc.), are placed individually on the map; players can buy industries, and also build processing industries wherever they like; processing industries have limited capacity, but they can be upgraded.
Just as Railroad Tycoon II, the game contains a campaign with several scenarios, presented by continent - North America, Europe and the World. The campaign interface is an interior of a railway museum, with the voice of the elderly eccentric museum guide from RT2.
North American missions:
* Go West: New York State & New England, 1840-66.
* Germantown, USA: Midwestern USA 1850-80.
* Central Pacific: San Francisco-Salt Lake City, 1855-76.
* Texas Tea: Texas & northeastern Mexico, 1888-1918.
* The War Effort: Mid-Atlantic USA, 1941. Tactical scenario.
* The State of Germany: Germany, 1848.
* The Flying Scotsman: Great Britain, 1848-65.
* Crossing the Alps: Venice-Munich-Zürich, 1875-1910.
* The Third Republic: France, 1871-96.
* Orient Express: Balkans, 1880-1914.
* Argentina 1880-1909.
* Rhodes Unfinished: Eastern Africa, 1902–33
* Japan Quakes: Japan 1964-85.
* The Seeder: Greenland, 2050. Tactical scenario.
* Dutchlantis: Western Europe, 2021-51.
* A chip off the Old Block: California, 2050-80.
Besides these, the game contains several stand-alone scenarios, such as post-war Italy, France, Western Europe in 1990, Australia, Germany and more.
Loco Commotion extra content
A train based puzzle game included on the Play Disc as a 141MB optional extra. Loco-Commotion involves solving route and shunting puzzles by moving trains at precise times over increasingly difficult environments throughout the multiple levels.
Coast to Coast expansion pack
The freeware expansion pack Coast to coast contains some new locomotives, maps and scenarios. Among the scenarios are imperial Russia and the People's Republic of China. There are unusual scenarios as well; including one in which the United States never underwent the Revolution.
With the release of the Coast to Coast Expansion pack, in addition to creating maps and scenarios, players were provided with tools to create customs logos, locomotive skins, and players. There are now more than 200 user created scenarios and 100 custom logos available.
Other mods have been created including new locomotives, rolling stock, industries and other building types to enhance gameplay.
Railroad Tycoon 3 - Trainmaster
RT3-Trainmaster is a player-community created super mod that completely alters the Railroad Tycoon 3 game play. It was initially designed to provide a platform for RT3 to play on Windows Vista and extend the playing life of the game. RT3-Trainmaster requires a fully installed copy of RT3 to play. It was released in the Spring of 2010.