This module is a replacement for the built-in captcha of OpenCart 1.5.x.
It's much better than the original for numerous reasons.
Installation:
1. Upload the contents of the 'upload' directory to your store's root. 2. Go to admin panel -> extensions -> modules ->reCaptcha - Contact & Review and click install. 3. Go to admin panel -> extensions -> modules ->reCaptcha - Contact & Review and click edit. 4. Input your public and private keys in the fields. If you don't have them you can get them here: https://www.google.com/recaptcha/admin
The module requires vQmod. No core file replacements.