Custom loop request based on custom field

See WP_Query in Codex for info on how to query on custom fields.

$args = array(
    'posts_per_page' => -1,
    'cat' => 4,
    'meta_key' => 'point_score',
    'orderby' => 'meta_value_num'
);

$points_query = new WP_Query( $args );

while( $points_query->have_posts() ):
    $points_query->the_post();
    the_title();
    echo ' : ';
    echo get_post_meta( $post->ID, 'point_score', true );
endwhile;