Underrated: Transport Fever. Admittedly I feel like a loser when I am sitting there watching my little locomotive trains run by and I'm just enjoying the scenery, and I have nothing with trains all together. But something is incredibly pleasing about making a functioning railroad system and seeing all the different transport modes come together to form a whole is... incredibly satisfying. 

There are other games out there that do more or less the same (Cities Skyline etcetera) as Transport Fever isn't really just a transport game either, it's not a railroad tycoon game. The way they handled city growth is incredibly interesting and I like how dynamic it feels and how it feels like I can influence the city growth if [i]I[/i] play the game right and do something that requires thought rather than slapping down some zones. 

TL;DR Transport Fever is great game, shame it's overlooked by people in favour of other games.