Another interesting way. This will take anything in [], and prompt for a word of that type. This eliminates the need to hard-code adjectives, adverbs, nouns, etc. Your file can look like

The [noun] [past-tense verb] over to [proper noun]
and soon [future-tense verb] to the [place].
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This allows you more flexibility in what you want them to input

!/usr/bin/perl -w

use strict;

my $story;

{
   local $/ = undef;              #Get everything
   $story = <>;
}

while($story =~ /\[(.*?)\]/g) {   #Find anything in []
   print "Give me a $1: ";
   my $val = <STDIN>;             #Get a value for it
   chomp $val;
   $story =~ s/\[$1\]/$val/;      #And sub it in
}

print $story;
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