At its heart, Rail Nation is a time management game that can be very rewarding to play as many aspects of this game are well-designed, including the economic system which is multi-faceted and reflects the technology and economic realities of the era. The game's isometric perspective provides a bird's-eye view, giving players a fresh and engaging way to interact with the world they're building.
Besides Rail Nation's well-designed economic system that is hyper-realistic, the game does live up to its name as a "Rail Nation" as it can also be seen as a train simulator game - thus being both a "rail/train" game as well as a "nation" building MMO games. With different tracks and types of engines/trains to develop and research, you may find yourself spoilt for choice.
Of course, with a complex game comes opportunities for discussion. This complex game requires different strategies for different playstyles, and joining a big corporation/city to aid in their efforts is the way to go. Think of it as a "guild" or a "clan", where you can discuss everything related to the game or anything off-topic. After all, it is much stay motivated when playing a game in which you have deep social roots and are able to get the advice you need!