Doraemon: Nobita and the Tin Labyrinth

Nobita's father receives a mysterious key in the mail that leads the gang to a hidden underground kingdom called Chachachaca, a paradise built entirely by robots serving the last remnants of a civilization. When the mechanical utopia's master computer turns tyrannical and traps their friends, Nobita and Doraemon must navigate the labyrinthine robot city to set everyone free. A grand science-fiction adventure full of imagination and heart.