start:
$mynum = int(rand(100));
$mynum = $mynum +1;
print "Game started! \nThe objective of the game is to work out which number I'm thinking of. \nThe number is between 1 and 100. \nStart guessing!\n";
print "For development purposes, the number is $mynum\n";
userinput:
$myguess = <>;
if ($myguess =~ m/^\s*\d+\s*$/) {
  if ($myguess > $mynum) {
    print "Your guess was too high! \nTry a lower number.\n";
    goto userinput;
  }
  elsif ($myguess < $mynum) {
    print "Your guess was too low! \nTry a higher number.\n";
    goto userinput;
  }
  elsif ($myguess == $mynum) {
    print "That was the number I was thinking of!\n";
    playagain:
    print "Play again? (y/n)\n";
    yesno:
    $yesno = <>;
    if ($yesno != m/^\s*(y|n|yes|no)\s*$/i) {
      print "That's not a valid response\n";
      goto playagain;
    }
    elsif ($yesno =~ m/^\s*(y|yes)\s*$/i) {
      goto start;
    }
    elsif ($yesno =~ m/^\s*(n|no)\s*$/i) {
      exit 0;
    }
  }
}
else {
  print "That's not a valid input. \nPlease input a number between 1 and 100.\n";
  goto userinput;
}