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="MonstrumMM2|58" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Hlavní strana" />
      <page pageid="11" ns="0" title="Might and Magic 1" />
      <page pageid="12" ns="0" title="Might and Magic 2" />
      <page pageid="13" ns="0" title="Might and Magic 3" />
      <page pageid="14" ns="0" title="Might and Magic 4+5" />
      <page pageid="18" ns="3" title="Diskuse s uživatelem:Majk" />
      <page pageid="405" ns="1" title="Diskuse:Corakovy zápisky" />
      <page pageid="485" ns="1" title="Diskuse:Corakovy zápisky/2012-1" />
      <page pageid="490" ns="0" title="The Chaos Conspiracy" />
      <page pageid="512" ns="0" title="Jak na staré systémy/DOSBox/Základy" />
    </pages>
  </query>
</api>