Hiddy captcha 1.5.1

This plugin provides you an easy captcha without javascript, without images, without math. Only a few of CSS and a few of server side.
An hidden text input is placed in comment form a human cannot see it so a human cannot compile it, a spambot otherwise see the text input and is forced to compile it.
The plugin check the existence of this text input and check if it has a value or not. It drops all comment with a value in the text input as spam.
Really simple and powerfull antispam system. Low CPU usage and no access to DB.