Simutrans is a freeware transportation simulator that runs under
Windows, Linux, and a few other operating systems (Apple Macintosh
with Intel processors, BEOS). It's similar to Transport Tycoon,
Transport Tycoon Deluxe and Transport Giant.

You take on the role of operating a transportation company, and your
goal is to get goods of various kinds, as well as passengers and mail,
from one place to the next.

Don't be fooled by the tile-based graphics - this is a very complex
game, and it is constantly evolving, with new features being added. It
is a living game, and consistently being made better and better.