The first child is an Engine. The second child locks his arms around the waist of the Engine, bites into the back of the Engine’s neck & holds there; the third child joins the second in a similar way. These three form the Freight Train. Soon the skin of their mouths grow over the bite marks & the skin of their arms grows into the skin of the others’ waists & the three become one child, sharing blood & nerves & emotions.
An extra child tries to hook onto the back of the Freight Train, thus attempting to form a Caboose. When the extra child succeeds in hooking on he thinks he is the caboose, the extra child is not part of the Freight Train & the Freight Train wants the extra child gone. The Freight Train whips itself vigorously in order to extract the extra child. The game ends when the Freight Train derails.