OpenTTD
An open source business RTS game.
Based upon the popular Microprose game "Transport Tycoon Deluxe", OpenTTD is an open source business strategy game in which you compete against rival companies by transporting passengers and various goods by road, rail, sea, or air for profit. OpenTTD stays close to the original while offering some enhancements, including larger maps, stable multiplayer mode for up to 255 players in 15 companies, and more methods and means of transport.
