The cat Aptcha

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.

Captchas are not hard to automate though.