`evaluate_board`

Glancing over the program, this looks like a nice fat target
Two big blocks like this one:

   360      foreach $x (0..2) {
   361          if (
   362              ($squares->[$x][0] eq $squares->[$x][1]) and
   363              ($squares->[$x][1] eq $squares->[$x][2]) 
   364             ) {
   365              $winner = $squares->[$x][0];
   366              return $winner;
   367          }
   368      }
            ...

Also a special case for the diagonals
There are only 8 ways to win in Tic-Tac-Toe
How can an analysis of 8 items require 21 lines?