$squares = array();
$squares[$fx . 'x' . $fy] = (string) $minefield[$fx][$fy];

if ($minefield[$fx][$fy] === 0) {
    $check = array();
    $check[] = $fx . 'x' . $fy;
    while (true) {
        foreach ($check as $k => $v) {
            list($_x, $_y) = explode('x', $v);
            unset($check[$k]);
            if ($minefield[$_x - 1][$_y - 1] === 0 && !isset($squares[($_x - 1) . 'x' . ($_y - 1)])) {
                $check[] = ($_x - 1) . 'x' . ($_y - 1);
                $squares[($_x - 1) . 'x' . ($_y - 1)] = 0;
            }
            
            if ($minefield[$_x][$_y - 1] === 0 && !isset($squares[($_x) . 'x' . ($_y - 1)])) {
                $check[] = ($_x) . 'x' . ($_y - 1);
                $squares[($_x) . 'x' . ($_y - 1)] = 0;
            }
            
            if ($minefield[$_x + 1][$_y - 1] === 0 && !isset($squares[($_x + 1) . 'x' . ($_y - 1)])) {
                $check[] = ($_x + 1) . 'x' . ($_y - 1);
                $squares[($_x + 1) . 'x' . ($_y - 1)] = 0;
            }
            
            if ($minefield[$_x - 1][$_y] === 0 && !isset($squares[($_x - 1) . 'x' . ($_y)])) {
                $check[] = ($_x - 1) . 'x' . ($_y);
                $squares[($_x - 1) . 'x' . ($_y)] = 0;
            }
            
            if ($minefield[$_x + 1][$_y] === 0 && !isset($squares[($_x + 1) . 'x' . ($_y)])) {
                $check[] = ($_x + 1) . 'x' . ($_y);
                $squares[($_x + 1) . 'x' . ($_y)] = 0;
            }
            
            if ($minefield[$_x - 1][$_y + 1] === 0 && !isset($squares[($_x - 1) . 'x' . ($_y + 1)])) {
                $check[] = ($_x - 1) . 'x' . ($_y + 1);
                $squares[($_x - 1) . 'x' . ($_y + 1)] = 0;
            }
            
            if ($minefield[$_x][$_y + 1] === 0 && !isset($squares[($_x) . 'x' . ($_y + 1)])) {
                $check[] = ($_x) . 'x' . ($_y + 1);
                $squares[($_x) . 'x' . ($_y + 1)] = 0;
            }
            
            if ($minefield[$_x + 1][$_y + 1] === 0 && !isset($squares[($_x + 1) . 'x' . ($_y + 1)])) {
                $check[] = ($_x + 1) . 'x' . ($_y + 1);
                $squares[($_x + 1) . 'x' . ($_y + 1)] = 0;
            }
        }
        
        if (count($check) == 0)
            break;
        
    }
    
    foreach ($squares as $key => $value) {
        list($_x, $_y) = explode('x', $key);
        $squares[($_x - 1) . 'x' . ($_y - 1)] = $minefield[$_x - 1][$_y - 1];
        $squares[($_x) . 'x' . ($_y - 1)] = $minefield[$_x][$_y - 1];
        $squares[($_x + 1) . 'x' . ($_y - 1)] = $minefield[$_x + 1][$_y - 1];
        $squares[($_x - 1) . 'x' . ($_y)] = $minefield[$_x - 1][$_y];
        $squares[($_x + 1) . 'x' . ($_y)] = $minefield[$_x + 1][$_y];
        $squares[($_x - 1) . 'x' . ($_y + 1)] = $minefield[$_x - 1][$_y + 1];
        $squares[($_x) . 'x' . ($_y + 1)] = $minefield[$_x][$_y + 1];
        $squares[($_x + 1) . 'x' . ($_y + 1)] = $minefield[$_x + 1][$_y + 1];
    }
}