title: PHP Verification Codes CAPTCHA
body: <p>I run a game website so I have many users logged in and they can do certain things once every two minutes.</p>
  
  <p>I have a CAPTCHA system in places, and for some things it will always ask for a code, and for other things, it will ask once every 10 minutes.</p>
  
  <p>I have had some players use the auto submit feature on Opera, and my CAPTCHA system does stop them.</p>
  
  <p>My question is, how can I minimise the amount of times I am asking for a code, but still stop people using this auto-submit?</p>