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="Блоки|340" />
  </query-continue>
  <query>
    <pages>
      <page pageid="76" ns="0" title="Блоки и предметы" />
      <page pageid="189" ns="0" title="Радиомаяк" />
      <page pageid="327" ns="0" title="Белый камень" />
      <page pageid="329" ns="0" title="Плиты" />
      <page pageid="330" ns="0" title="Белая пыль" />
      <page pageid="331" ns="0" title="Седло" />
      <page pageid="337" ns="0" title="Блок белой пыли" />
      <page pageid="338" ns="0" title="Забор" />
      <page pageid="339" ns="0" title="Белая стена" />
      <page pageid="580" ns="0" title="McMMO" />
    </pages>
  </query>
</api>