OpenTTD is a free and open source port of Chris Sawyer's Transport Tycoon Deluxe. It is similar in concept to the Rollercoaster Tycoon series and was originally made by the same person. The focus of OpenTTD is building a cargo transport empire. From trucks to planes to ships to trains, OpenTTD has many transport options. Chief among them though is rail transport where OpenTTD’s depth in train networking is unparalleled.
When you attempt to join the server, be sure to click the button on the lower right that says “Find missing content online”. You will then be able to easily download the newGRFs that the server is using. NewGRFs are simple downloadable mods that you won’t be able to join without.
OpenTTD can feel overwhelming to learn at first, but once you get into it it's a load of fun to solve engineering problems and construct huge transportation networks.
