OpenBVE is a train driving simulator similar to Microsoft Train Simulator, but free. It has a version for Windows and Linux and is kept alive due to the contributions of the community in terms of routes, locomotives, cars (etc) . Which can be downloaded online.
We have many activities to choose from. Those of passenger services, can become long and somewhat stressful but are pretty good. The cabins of the machines (depending on the creator) are very well created, as well as many effects such as the spark of the third rail or the typical noises when crossing through a route. These are small details that create a good experience.
The graphics, as I said before depends greatly on the author. But in general are quite good. It uses OpenGL acceleration and the Windows version uses Direct3D, this allows you to enjoy the game with better graphics.
On the audio side, every route, every train has its own sounds. They are all very good, although it notes that it is a sound file generated by loop.
The controls are much simpler than in Train Simulator, at least they can be simplified to a few letters. But also depends on each train (diesel, electric, etc).
Honestly, the game is very good. I searched for a game like this and found nothing similar to it.
If you want to see some pictures, click on this link. OpenBVE is free and you can find it as OpenBVE at the Software Center of Ubuntu, but if you like the console, you can type in the following: sudo apt-get install openbve
You can also download the Windows version from the official website