The very first interactive movie.
This film was shown at the Czechoslovakia Pavilion at Expo '67, the World's Fair held in Montreal, Canada. An interactive presentation, the action stopped five times during the course of the film to allow the audience to vote on which way the story would proceed. The film was also shown at HemisFair '68 and, with new scenes added, at Expo '74.
Banned from Czechoslovakia by the communist party in 1972.