This GOTW is in honor of father's day. One of my earlier gaming memories was playing "A-Train" with my dad back on our old machine. It was published in the states in 1992, but it was first released even further back in Japan under the title: "A Ressha de Ikou" -> "Take the A-Train"
(Image and facts via Wikipedia) You can get the game to run on a DOS emulator, and I recommend it. It still holds its own as a well designed piece.
Studio: Artdink
Format: PC, 1 Player, DOS - Emulator version here.
Core Mechanic: Build and operate a railroad which indirectly causes urban growth.
Control: 3rd person isometric via HUD.
Design Notes: The first thing to note is the beauty of A-Train's simple aesthetic. I like the sunset animation better than a lot of stuff I've seen on current gen consoles. The city itself sprouts up in a beautiful and procedural way as your railroad supplies building materials and passengers to stations.
In terms of gameplay, there are two feedback mechanisms that motivate rail building. First are the cities, which spawn based on how rail accessible areas are. Second is the underlying economy system: a simplified numeric financial system of the business end of running a rail system. As a combination they offer a well designed core mechanic that is enjoyable to this day. It makes you feel like you are running a railroad.