I am looking for the title of an old Sci Fi movie. I was in color. Humanity was living under ground after an atomic war. The landscape was barren. They had force fields set up to keep out the mutants (and away from their food). During the film the people befriended a mutated human who only had one leg. At the end of the movie the caves were overrun by the mutants and scientists opened a window to the future and the survivors went through.
