Simutrans is a freeware transportation simulation game.

Your goal is to establish a successful transport company. Transport passengers, mail and goods by rail, road, ship and air. Interconnect cities, districts, public buildings, industries and tourist attractions by buiding a transport network you always dreamed of.

Control and watch your finances and the traffic of your vehicles and goods. Start in 1880 and finish in 2050. There will be new vehicles and buildings throughout this time.


Not open source

Sorry to say it, but this is not open source. Game is distributed under Artistic License 1.0, which is neither OSI nor FSF-approved. But the actual reason is that there's an explicit NonCommercial note referring to the media, thus violating point 1 of the Open Source Definition.