Subway systems are circulatory systems, moving the lifeblood of a city from place to place beneath its skin. In the game Mini Metro, you get to be the engineer who maps out the veins, connecting all the stops in colorful tangles that keep the city moving as it grows around you.

Some of the biggest cities in the world are your transportation playgrounds: London, Paris, Hong Kong, New York, Berlin. Familiarity may offer a slight advantage as well; although I was complete garbage at building a tube for London, when I tried designing a subway system in my former home of New York City, it felt far more intuitive.

Although the map above looks complicated, and kind of is, the game begins very simply. You start with three stops, each one labeled with a shape—circle, triangle, square—and you connect them. The passengers at each stop are represented by shapes of their own, and your goal is to build lines that will efficiently route them to their similarly-shaped destinations. Unlike real life, these passengers aren't interested in reaching specific places; as long as a stop matches their shape, they'll happily disembark.

Things get more complicated as new stops pop up throughout the city, often in very inconvenient places, and you have to figure out how to link them in without turning your metro map into an inefficient mess. Fortunately, you can demolish and build new lines instantaneously, but if you make too many passengers wait for too long, and it's game over. Read the rest