Simutrans

From Wikipedia Simutrans is a cross-platform simulation game in which the player strives to run a successful transport system by transporting goods, passengers, and mail between places. Along with OpenTTD, Simutrans is an open source remake of Transport Tycoon. Simutrans was originally written by Hansjörg Malthaner but it is now maintained and developed by a small team which releases bug fixes, changes or new features for the game.