OpenBVE
openBVE is an independently developed open source train simulator. Although the name and logo which originally came from BVE Trainsim, the open-source train simulator was developed from scratch and features support for train exteriors, animated 3D cab environments and animated scenery. Internally, openBVE makes use of OpenGL for rendering, as well as OpenAL for three-dimensional positional audio.
The program is noted for its cab ambience and realism. It is currently distributed in the public domain, along with full C# and C source code.
Read more about this topic: BVE Trainsim