There are ten cities in your underground country, each linked by 1 to 8 tunnel segments. Each time you stop the pistons in all the tunnels connecting two cities, you will get bonus points, and also will have a chance to look at the map. This let's you know how you are doing, and also gives you time to pause.
Rescuing some cities will also give you bonus bombs or trolleys.
Occasionally, flashing boxes will appear beneath the pistons. These are special events, they can either help you (they may give you points, or bombs) or they can hurt you (cut the strength of a stack in half). To earn them, you have to flip a block through them before they disappear or a piston reaches them.
