Captcha Alternative

This is a mockup of the captcha alternative for my blog (redesign in the works). The user has to correctly click the correct colour - if they get it wrong then they must do it correct 2 times etc. If they get it wrong 3 times then they are locked out for 12 hours. They are 'verified' for 3 form submissions before they have to re-verify themselves. I think the circle looks weird - any suggestions or shall I just get rid of it.