You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="Silent_Hunter|159" />
  </query-continue>
  <query>
    <pages>
      <page pageid="100" ns="0" title="Silent Hunter IV" />
      <page pageid="108" ns="0" title="Silent Hunter III" />
      <page pageid="147" ns="0" title="Silent Hunter IV. Вспомогательные программы" />
      <page pageid="148" ns="0" title="Silent Hunter IV. U-Boat Missions" />
      <page pageid="150" ns="0" title="Silent Hunter IV. Редактор миссий" />
      <page pageid="151" ns="0" title="Silent Hunter IV. Моды" />
      <page pageid="152" ns="0" title="Silent Hunter V" />
      <page pageid="153" ns="0" title="Silent Hunter V. Редактор миссий" />
      <page pageid="154" ns="0" title="Silent Hunter V. Вспомогательные программы" />
      <page pageid="158" ns="0" title="Silent Hunter V. Обновление 1.1" />
    </pages>
  </query>
</api>