RewriteEngine on
RewriteRule ^category([0-9]+)/?$                                        view_category.php?id=$1                   [L]
RewriteRule ^forum([0-9]+)/?$                                           view_forum.php?id=$1                      [L]
RewriteRule ^forum([0-9]+)/page([0-9]+)\.html$                          view_forum.php?id=$1&page=$2              [L]
RewriteRule ^forum([0-9]+)/([0-9]+)\.html$                              view_topic.php?id=$2&forum_id=$1          [L]
RewriteRule ^forum([0-9]+)/([0-9]+)-([0-9]+)\.html$                     view_topic.php?id=$2&forum_id=$1&page=$3  [L]
RewriteRule ^users/([0-9]+)\.html$                                      view_user.php?id=$1                       [L]
RewriteRule ^(selected|popular|recent)\.html$                           index.php?show=$1                         [L]
RewriteRule ^(selected|popular|recent)-([0-9]+)\.html$                  index.php?show=$1&page=$2                 [L]
RewriteRule ^forum([0-9]+)/(selected|popular|recent)\.html$             view_forum.php?id=$1&show=$2              [L]
RewriteRule ^forum([0-9]+)/(selected|popular|recent)-([0-9]+)\.html$    view_forum.php?id=$1&show=$2&page=$3      [L]