Manoeuvring a plane is a challenge, but once you take it to the skies, there is not much to see around you! Where as in MSTS, you drive a train along real (or fictitious) routes. That was wonderful but I never fell in love with that as I did in Train Simulator. You can become a passenger also (but that's not much fun anyway). It is estimated that 500,000 people in the world regularly play this game (and the number is increasing). Rather you enjoy riding (I rather say driving) a train with realistic constraints. You don't race with anyone or don't solve a puzzle. Train Simulator is the best game I have ever played on PC.
It is not meant to be an introduction of the game. This article reflects my personal feeling about Microsoft/Kuju Train Simulator (MSTS for short) PC game.