return true to win

<?php

function foo($x)
{
    // This level is slightly different than level 12
    // the comparison is != instead of !== ;)
    return $x[123456] != null
        && $x[123456] === $x[123457];
}

Absolute best score: 13

Level 1
Level 2
Level 3
Level 4
Level 5
Level 6
Level 7
Level 8
Level 9
Level 10
Level 11
Level 12
Level 13
Level 14
Level 15
Level 16