Hello. free game that is open-source. all-in-all, this game has some pretty cool sounding features. not particularly new, been around seems since 2004. so, it probably has tons of community made content laying around. will have to give this one a try myself someday!
OpenTTD
Game Description:
OpenTTD is a business simulation game in which players earn money by transporting passengers and cargo via road, rail, water, and air. It is an open-source remake and expansion of the 1995 Chris Sawyer video game Transport Tycoon Deluxe.