Leiden is going dark tonight, one place at a time. A mosque, a museum, a church, a butcher's shop: one of them goes out, and a red ring starts shrinking around it. Tap the place and its fuse box opens. There are four wires on one side and four sockets on the other. Drag each wire to the socket of its own colour. On the fourth one, the light comes back. Watch the ring. From the moment a place goes dark you have twelve seconds. Miss them and that place stays dark for the rest of the night. Miss three and the whole city goes out. A night lasts a minute and a half. At the end you see how many lights you brought back, and which places stayed dark. Every place you save flies into your collection at the top right. Open it and each place tells you who it is. There are thirty-eight of them, all real places in Leiden, each one exactly where it stands on the map.