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="TOC_limit|81" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page" />
      <page pageid="5" ns="0" title="Building Bitfighter" />
      <page pageid="20" ns="0" title="Programming robots" />
      <page pageid="27" ns="0" title="Programming levelgens" />
      <page pageid="61" ns="10" title="Template:TOC right" />
      <page pageid="62" ns="2" title="User:Raptor" />
      <page pageid="85" ns="10" title="Template:Column-width" />
      <page pageid="86" ns="10" title="Template:Column-count" />
      <page pageid="88" ns="0" title="Bitfighter Wikipedia Submission" />
      <page pageid="97" ns="0" title="Scripting 018" />
    </pages>
  </query>
</api>