You'll probably have to add it to your facebook account (assuming you have one) to play it. It only takes about 5 minutes to play and it tells you your brain size based on how well you do. Would be interesting to have a league to see who has the biggest brain on hukd.
I'll kick us off by posting my score of 1992cm³.
What I don't understand is how on earth the top people have scores such as 3993cm³? I've played it 8 times now and don't see how anyone could get much higher than about 2500.