Its a rather difficult kind of Psycho technical test being done by Lufthansa in Hamburg. Gulf Air uses these tests to screen their new pilots or to screen "soon to be " captains before their upgrades.
Word goes that if you ever fail these tests your name appears on some kind of list and every airline in the world has access to it.....
I do not know, most possibly this is some kind of rumour spread be angry/frustrated pilots who failed the thing!
It most probably is difficult but so what....I "d rather be flying for a company wth well screened crews than the other way around.
Greetz