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="Bear_route.jpg|6292" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1421" ns="0" title="Batch Encoding" />
      <page pageid="5456" ns="0" title="Mighty Bomb Jack (NES)/Game Mechanics" />
      <page pageid="5616" ns="0" title="Batman: Arkham Asylum/Tricks" />
      <page pageid="5949" ns="0" title="Bastion" />
      <page pageid="5961" ns="0" title="Bastion/Roathus Lagoon" />
      <page pageid="6066" ns="0" title="Ikari Warriors/Game Mechanics" />
      <page pageid="6289" ns="0" title="Amped 2/Mountains and challenges" />
      <page pageid="6292" ns="0" title="Amped 2/Routing" />
    </pages>
  </query>
</api>