The object of the game is to deliver as many people to their destinations as you can. To accomplish this, players place route markers on the board to connect passengers to their destinations. However, the destination types (work, bar, home) vary from turn to turn, so you can follow certain passengers as they make their way through the daily grind.
Players may buy more buses (they start off with one), build onto their bus route, bring new passengers to the city (via the trains), expand the city by adding more buildings, and run their buses. There is another option, the clock, but more on that later. The action board has one other clever feature. On some actions, route expansion and building, the first player to choose that action actually gets to execute the action last! Which leads to some interesting games of chicken and some painful decisions.
Buying more buses allows a player to carry one more passenger every time they run their buses - hence scoring, in the best case, one more point. Depending on how the city gets built, however, finding lots of passengers on the street can be tricky.