...
#my $words = @words;  # just use (scalar @words)
chomp(my $word = lc($words[int(rand(scalar @words))]));
my @chars = split//,$word;
my %chars = map { $_ => 1 } @chars;
...
while ($turns > 0) {
   ...
   foreach my $char (@chars) { # split not needed
   ...
   else {
      #my %word = map{$_=>1}split(//,$word); # not needed
      if (exists($chars{$guess})) {  # changed %word to %chars
   ...