Simutrans is a freeware. - Official web
Simutrans is a game which is similar to Simcity but it focuses on transport developing.
You could develop your own bus routes, tram routes, monorail routes, ship routes or even plane routes in this game by simply clicking using your mouse or keyboard.
This game is avaliable on Windows, Linux and Mac. And it have various packs, depending on your choice. pak128 is currently the most common pack played in Simutrans.
P.S. Please drive right-hand-sided cars in Simutrans!
Screenshots:
You could develop your "kingdom" by making railways or airplane routes
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Tired of trains and planes? Why not trying ships?
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And everyone's favourite: buses!
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