Yep, and that page links you to http://www.gchq-careers.co.uk/cyber-jobs/ http://www.gchq-careers.co.uk/cyber-jobs/ which is equally linked to by anyone who did

Yep, and that page links you to http://www.gchq-careers.co.uk/cyber-jobs/ http://www.gchq-careers.co.uk/cyber-jobs/ which is equally linked to by anyone who didn't solve the puzzle but just looked on http://www.gchq-careers.co.uk/Jobs/ http://www.gchq-careers.co.uk/Jobs/ That said: you would never expect them to use the online test as a deciding factor in interviewing people, they can do tests as part of the application process. Really it's just a marketing campaign, and a way to let people self-test themselves to see if they are suitable.