add_rewrite_rule('^blog/games/(a-z|z-a|most-recent|most-viewed)(/page/([0-9]{1,}))?\.html$', 'index.php?blog_category=game-guides&index_sort=$matches[1]&paged=$matches[3]', 'top');

after adding above rule I found 404 for below URL

http://localhost/blog/games/most-recent/page/2.html and http://localhost/blog/games/most-recent.html

also, I can find my rule in get_option( 'rewrite_rules' ). games is blog category