This year, I had my first experience of something that as a graduate, it's quite likely that you too will fall victim to in the coming months; I attended an assessment centre day, pitted against other graduates in the job-hunting equivalent of The Hunger Games.
Before I get into it, however, I feel that I should begin this post with something of a disclaimer. I'm afraid to report that in actual fact, the assessment centre was about as far as I got with this particular company (a big ol' multinational, FYI, so I'm assuming it was pretty standard assessment centre fare).
'It's like the blind leading the blind!' I hear you cry. Possibly, but bear with me, dear reader, for while I might not have been deemed worthy of the job that day, I did however learn a fair bit about what goes on during these exercises in enforced torture. Think of me as the Haymitch to your Katniss - slightly unreliable (though not, incidentally, an alcoholic), but someone who can at least speak from personal experience. It's best to know your enemy, as they say, and I can hopefully provide you with some idea of what to expect.

Step one: the introductory schmoozing

At the beginning of the day, as you gather with a group of graduate hopefuls, you can expect a fair amount of company back slapping to go on, in true Capitol style. After giving you a breakdown of the day, HR big shots will be extolling the virtues of working for their company, and if they're a fairly big corporation - which seems likely, given that they can put one of these days on in the first place - expect to see PowerPoints and videos and all sorts of bells and whistles informing you of all the great things they do.
Considering that this generation of graduates are emerging from the comforting cocoon of university into a fairly unwelcoming job market, this all felt a tad unnecessary to me, if I'm honest (and HR big shots, if you're reading, there's really no need for the hard sell, we wanted the job before we even got there!). But it's par for the course, I'm afraid, so if like me you're naturally inclined to cynicism, prepare to feel a little nauseated.
Prepare in addition to almost certainly partake in some cringe-making networking exercises - you know the kind, the 'Who would be at your ideal dinner party?' type questions. This is your first chance to introduce yourself and make the right sort of super enthusiastic and likable impression, so even if little else, you can at least come prepared for the day with a blinder of a dinner guest.

Step two: the group task

Once the cheesy introductions are over, it's likely that you'll be siphoned off into groups to work together, all the while being observed from the side lines. At my assessment day, we weren't told what they looking out for in our handling of this task, but I'm going to hazard a guess at it being a test to see how quickly you come up with ideas for whatever's been set, how you go about communicating them, and uh, whether or not you're a megalomaniac.
We were provided with a brief to set up and promote an event with a particular theme, within a certain budget. Don't make my mistake here, and despair fairly quickly of ever getting your voice heard over the din of passive aggression. There are likely to be others who fire off on all cylinders, taking charge of the marker pen and very shortly the entire room. But just because they've got the loudest voice, doesn't mean they've necessarily got the best things to say - so do your best to get your points across, and listen and respond constructively to others.
General failings encountered in my group that are worth learning from include not keeping an eye on the time, and not leaving enough to properly sort out who was saying what in the following presentation, getting bogged down in minor details that probably weren't really worth all the time invested in them, and failing to involve every member of the group (some virtually mute group members were clearly feeling even more defeated than I was).

Step three: the individual interview

I won't launch into the ' how to do the perfect interview' spiel - I'm clearly no authority on the matter, and the usual applies, of course - if you do your homework on the company, and come across as enthusiastic and as capable as you can, then there's really not much more they can ask.
But what I will say is that if your assessment day follows the same format as mine, where the interview was the final thing you had to endure, then the worst will definitely already be over. If this is the Hunger Games, you're well on your way back to the Capitol.
For me, the build-up to an interview is generally far worse than anything that happens within the actual interview itself. But by the time it came around on the assessment day, all of my usual pre-interview nerves had been used up hours ago, and I was 'shockingly cavalier', as Juno might say, about walking in there. Think of it this way - you simply have to go into a room and cast aside your British modesty to tell a couple of people just how brilliant you are. With any luck, they'll agree. But if the odds weren't quite in your favour, then don't despair - remember, you did well to get this far into the recruitment process, and hey, you've survived!