Another (for me) bug, every time the time goes to zero and the captcha is proposed, the first solve of it don't open the possiblity to play again but is reloaded the page with another captcha and, so i have to solve it twice to start a naw session of playing.
This actually happens quite often, regardless of the page having been left opened or fully reloaded. The CAPTCHA sometimes just doesn't work and acts like it was answered wrongly, even if the the answer was perfectly correct.
Anyway, even if this kind of CAPTCHA seems to be rather buggy, it's still
a lot better than having to parse an unreadable mess of random characters.