There has been good progress over the last few weeks especially by Dave, and now there are instructions for setting up FreeTrain from SVN so that it ‘runs’ on Linux/Mono/SDL. The caveat is that it still has problems, but the situation is improving almost every day so if you feel brave - or even better if you think you could help out - have a go and see how far you get.
Also there has been some development, for the first time in a long time, in the Japanese version under the moniker ‘FreeTrain Railways’ which we will hopefully be able to pull into our version - or ideally bring the two development worlds together. Work has already begun on internationalizing the game (this project was originally an English-only translation) so soon we should be running in both English and Japanese so there is scope for consolidating development.