Train simulator

A train simulator (also railroad simulator or railway simulator) is a computer based simulation of rail transport operations. They are generally large complicated software packages modeling a 3D virtual reality world implemented both as commercial trainers, and consumer computer game software with 'play modes' which lets the user interact by stepping inside the virtual world. Because of the near view modeling, often at speed, train simulator software is generally far more complicated and difficult software to write and implement than flight simulator programs.
Industrial train simulations.
Like flight simulators, train simulators have been produced for railway training purposes. Driver simulators include those produced by:
Signaller training simulators have been developed by Funkwerk in Germany, The Railway Engineering Company (TRE) in the UK, OpenTrack Railway Technology in Switzerland, and PS Technology in the US.
Consumer train simulation.
There are two broad categories of train simulation video games: driving simulation and strategy simulation.
Driving simulation.
Train driving simulation games usually allow a user to have a "driver's view" from the locomotive's cab and operate realistic cab controls such as throttle, brake valve, sand, horn and whistle, lights etc.
Train driving simulation software includes:
The PC game "3D Ultra Lionel Traintown," amongst some others, give a different experience to driving, by being in a 3rd person omniscient perspective, controlling the trains from a bird's eye view.
Peripherals specifically designed for use with driving simulations include RailDriver by US manufacturer P.I. Engineering. RailDriver is a programmable desktop cab controller with throttle, brake lever and switches designed to work with "Trainz", "TrainMaster", "Microsoft Train Simulator" and "Rail Simulator".
Strategy simulation.
Railroad-themed strategy simulation video games are focused mostly on the economic part of the railroad industry rather than on technical detail. The "A-Train" series (1985 to present) is an early example. Chris Sawyer's "Transport Tycoon" (1994) was an influential game in this genre, spawning remakes such as "Simutrans" (1999 to present), "OpenTTD" (2004 to present) and Sawyer's own "Locomotion" (2004). Sid Meier designed two railroad simulations: "Railroad Tycoon" (1990) and "Railroads!" (2006). The "Railroad Tycoon" series itself inspired other rail games such as "Rails Across America" (2001).
Other genres.
Some rail simulation games focus on railway signalling rather than economics. Examples include "The Train Game" (1983), "SimSig" (donationware) and "Train Dispatcher"
JBSS BAHN (shareware) focuses on simulating a complex railroad lay out.
PC-Rail Software have nearly 90 different signalling simulations, mostly based on UK locations.
History.
Train simulators are popular in Japan, where rail transport is the primary form of travel for most citizens. Train video games have been developed in Japan since the early 1980s, with Sega's arcade action game "Super Locomotive" (1982) being an early example, before more realistic train simulators emerged, such as Ongakukan's "Train Simulator" series (1995 debut) and Taito's "Densha de Go" series (1996 debut), as well as train business simulations such as the "A-Train" series (1985 debut).
One of the first commercially available train simulators was "Southern Belle", released in 1985. The game simulated a journey of the "Southern Belle" steam passenger train from London Victoria to Brighton, while at the same time the player must comply with speed limits, not to go too fast on curves and keep to the schedule. It was followed with "Evening Star" in 1987.
While commercial trainers on mini-computer systems had a longer history, the first two mass-market English 'computer game' railway simulators, "Microsoft Train Simulator" and "Trainz", arrived within a few months of one another in 2001 and could run on Intel 80386 microprocessor based systems. 
Before that, already in 1996, the free BVE was aviable to the public. Later on, the Open BVE, a free and open source project, was developed and re-written from scratch.
Some, like the wide-market release, "Microsoft Train Simulator" (MSTS), are written and modeled for the user mainly interested in driving. Others, like MSTS's principle rival, "Trainz", were aimed initially primarily at the rail enthusiast-hobbyist markets, supporting features making it possible to build a virtual railroad of one's dreams. Accordingly, for four years "Trainz" releases bundled a free copy of Gmax digital model building software on each CD-ROM, hosted an asset swap website ("Trainz" Exchange, later the "Trainz" Download Station), encouraged user participation and dialog with an active forum, and took pains to publish in-depth how-to model guidelines and specifications with its releases.
Several other later challengers as well as "Trainz" (with a series of upgrades) soon matched or eclipsed MSTS's driving experiences one way or another. "Railsim", actually a successor using the MSTS game engine upped the challenge to the aging MSTS by adding much improved graphics, so "Trainz" did as well, but also added interactive industries and dynamic driving features such as product loading and unloading, load-sensitive physics modeling affecting driving and operating and user interface changes to improve user experience (UX), such as a free-camera mode allowing roaming away from the train cars, free and clear of the train being operated-while still controlling it. This latter makes particular sense given the dearth of an assistant on a walkie-talkie while operating a train during coupling operations or other position sensitive tasks such as loading and unloading. "Railsim" and a couple of others came and went out of business, and "Railsim" was reorganized as "Rail Simulator" with the software company that wrote MSTS as its core, while MSTS aged and never did get upgraded as Microsoft had once begun and announced. In the last few years, "Rail Simulator" has changed its name to "Train Simulator".
As the world market has shaken out, Australian "Trainz" in 2014-2015 upgraded itself with "", still servicing the wider route builder and driving markets, but now matching the 64-bit computing and graphics of "Train Simulator." In the same five-year period, train simulators have moved to pad computer and phone platforms.