My son is a train fanatic, so I decided to check train games in Linux for him. For our Ubuntu computer at home there were two packages readily available: Ri-li, but better still openBVE.
Ri-li is a simple game, but for a 4-years-old perhaps still a bit difficult.
openBVE is a proper train simulator (definitely too difficult for my son to control, but probably fun as a vicarious driver), and it was installed properly on Ubuntu 9.04 through the Synaptic Package Manager, but not in 9.10, so I had to install it through Wine. All is clearly explained in Rail Sim Routes. This YouTube Video shows it off!