[Thor]

I quit a very, and I mean VERY fun game a few months ago because everytime you would click - anywhere - more than 6 times per 30 seconds, it would bring you a GD image to make sure you were a human.

The problem was, over being very annoying, that it's not always clear and easy to see those letters and numbers and after 3 fails, you were banned for an hour. 2nd ban was 4 hours and so on, 5 (inside 1 month I think) and you were out for good, unless you could convince the admins you were just a "dumb" human that can't read 2 letters written over each other.

Don't harass your players too much unless you don't care and have 10's and 100's thousands of them to replace those everyday quitters.