I just wanted to let you know that the link for Simutrans above is outdated, as of a couple of years ago.

The best and most official link is the Simutrans International Forum, located at http://forum.simutrans.com/

You can find the latest version there to download — and we have versions for Linux, BeOS, Mac, and Windows, as well as multiple paks (like graphics sets) to download, including, for example, one where the graphics were drawn by hand and scanned in – it’s very striking and cool!