This post is a ideia of an anti-bot system based in a game named waikfu. Aptcha have 1% to shows up in some node asking you to type a code "128" for example, if you dont type the code correctly, he will debuff you with less 50% chance of gathering item and there is 30% now Aptcha shows up.. If you wrong again you will miss all things and Aptcha have 50% to shows up.
If you found Aptcha and type correctly, he will give you a bonus of what you collected.

In some magical way, all wrong captcha could be send to GM team for further investigation of using bots and banning them.