It's a right pain in the arse when you play earth on your phone. Is there a pattern for when it asks for asks you to do it? Likes hours or every 10th log in?
Most the time it reckons I've got it wrong when I know I ain't

24 hours

do the bonuses and it wont ask you

I actually think it's 30 hours, but if you do the bonus captchas every 24 hours, it counts.

quit playing the game until they find a better way to detect bots. think i was failing capture simply because i hit the enter key instead of clicking on the button.

It gave me greek symbols to try to type in last week. Like a sorority house alpha beta theta symbols. lol

i've gotten math equations before :\

i use my phone most the time to get on earth. captcha is a big put off because when i answer correctly, it normally ends up overloading/crashing my phone browser and i have to login again, heh.

I know that if you don't have cookies enabled or something, even if you get the captcha correct it will just show you another one as if you failed. If that happens, all you have to do is refresh the page and it will move past it.
Happens to me at work

Gallery: yea i got those once too, imagine greek letters and those mirrored.