A lot of these train simulator games are a mix between job simulation and arcadey fun. To give a big example of the latter, in the Densha de GO!! games, the goal is to follow all the speed limits, brake gently without allowing the G-forces to exceed a certain amount, and to arrive at the station exactly on time while stopping at the exact right spot to the millimeter.

For some people, just the fact that it's a simulation is enough to make it fun. But to many others, the challenge (and I can promise you it is quite difficult) is what makes it a fun game.

I've been playing these games for half a decade now, and I've only managed a zero zero once (meaning that you come to a stop exactly on time to the second and stop within 0.0cm of the marker.)