So I was closing down Steam this morning when a game called "Mini Metro" appeared in the sales queue. I looked at it and was intrigued, and after a couple of LP's on Youtube, I knew I had to buy it; it's downloading now.
Basically, it takes a real-world city- London, St. P, New York, Paris, São Paulo- and reduces it to a flat map with the water features. It'll then place a couple of different subway stations, indicated by different shapes- circles, triangles, squares- in the center of the city, and you have to connect them with lines. At each station, passengers will begin to queue, represented by small versions of the shape of station they want to go to. The game will give you new stations to connect as time goes on, and you can add extra lines and trains.
There's a catch, though- you can't let any station fill up too much. The standard station can hold six passengers in line before it becomes a time bomb, and stations can occasionally be upgraded to hold more passengers. When a station is over capacity, a timer starts ticking, which will then stop and reverse if a train arrives to load the excess passengers onto. If that timer reaches 0- represented by a circle around the station- you lose the game. So you really have to be good with system design, because trains can only go so fast, and hold only so many passengers. You can sometimes move trains and wagons to another line to relieve a station that's about to go kablooie, but that's a stopgap at best, and can't be relied on too much.
Also, I gotta plug the UI- it's absolutely gorgeous. It's based on the London Tube map, and has a very elegant, simple, intuitive feel- GUIs by Ikea.
Will have more to say once I've played some...