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>
    <allfileusages gafcontinue="Barbarian_on_battlefield.gif" />
  </query-continue>
  <query>
    <pages>
      <page ns="6" title="File:Back For Revenge (Allies) map large.png" missing="" />
      <page ns="6" title="File:Back For Revenge map large.png" missing="" />
      <page pageid="6959" ns="6" title="File:Badge of Courage artifact.gif" />
      <page pageid="3312" ns="6" title="File:Ballista.png" />
      <page pageid="8551" ns="6" title="File:Ballista portrait.gif" />
      <page pageid="8829" ns="6" title="File:Barbarian Breakout (Allies) map large.png" />
      <page pageid="8830" ns="6" title="File:Barbarian Breakout (Allies) underground map large.png" />
      <page pageid="8827" ns="6" title="File:Barbarian Breakout map large.png" />
      <page pageid="8828" ns="6" title="File:Barbarian Breakout underground map large.png" />
      <page pageid="4984" ns="6" title="File:Barbarian Lord&#039;s Axe of Ferocity.gif" />
    </pages>
  </query>
</api>