They're tricky, they're testing, they're downright infuriating. They'll make you laugh, they'll possibly make you cry and they'll almost certainly have you coming back for more, just to show them. Just to show them good! They are the hardest games you can find online.
Now, burying the needle on the Casual Girl Gamer hard-o-meter takes more than flooding the screen with overwhelming waves of bad guys - the candidates here are less bashing and blasting, more baffling, befuddling and bewitching. Indeed, there's hardly an enemy to be seen in our collection of brain teasers, tests of skill and just plain maddening fun.
That's because ultimately, as I found during my extensive research into these digitised versions of pure, mind-bending evil (in the nicest possible sense, that is), the real battle is often against one's own, occasionally dispiriting, lack of basic coordination and reactions.
Increpare's Primitive Pattern may be the most straightforward of the games in our list, but it is also one of the toughest nuts to crack. It bills itself as a treatise on Hegelian semiotics and invariant theory. After much in-depth rummaging around on Wikipedia, I think this means it's something to do with algebra and that bloke who captained the Germans against the Greeks in Monty Python's philosopher's football match.
The premise is as simple as the retro, low-fi graphics. Click nine circles in a three by three box in any sequence you like. Easy, right? To win, you must pick the second most popular pattern based on previous plays. Not so easy. Keep clicking away though, there's only something like 80 bajillion combinations. Play Primitive Pattern here.
2Poto and Cabenga
One button games can't be hard, can they? Oh, they can. Honeybug's creation starts off harmlessly enough with our heroes - who, fact fans, apparently take their names from the alter egos of secret language speaking twins Grace and Virginia Kennedy - riding across the plain.
Their unexpected separation thanks to a passing dragon sees the game switch to a split-screen, side-scrolling adventure as Cabenga (or possibly Poto) navigates the belly of the beast and Poto (or..well...) continues on the ground. From then on, avoiding (or squishing) various desert critters and dragon stomach bugs, speeding one partner up while simultaneously slowing the other one down and using coordinated moves to remove obstructing beasties is all down to your skill with a space bar. Play Poto and Cabenga here.
The irritating game that uses 100 per cent of your brain - Jeu Chiant does exactly what it says on, er, the tin. There's no story, no levels and no baddies or bosses. The challenge here is a load of balls. Well, two balls to be precise, which isn't really a load. Anyway, you have to keep one balanced on a see-saw while using a sliding horizontal platform to play keepy-uppy with another.
It's devilishy tricky from the off, requiring some frantic mouse work and that most dreaded of things (for the male mind at least) - multitasking. The despair of seeing one (or both) of your balls fly into oblivion is compounded by the withering assessments of your efforts, which are on the one hand entirely uncalled for and, in my case, basically true. Play Jeu Chiant here.
Speaking of multitasking, here's enough of it to reduce even the most hardy of souls to a gibbering mess. DiscipleOfFred's mind-blasting Flash sequel is four games within a game. On their own, none of them would be particularly challenging or entertaining of course, but put them together and even remembering the instructions becomes a Herculean feat of memory.
To make matters worse, you only actually play two of the four games at any one time, so even when you think you're getting the hang of simultaneously taking on one pair, you're suddenly presented with a new combination. Still, at least it doesn't compare you to a poodle or Paris Hilton. Play Multitasking 2 here.
Here's more games-within-a-game mischief in the retro 80s form of Morplee. In that spirit, I'll say it's the browser gaming equivalent of doing Black Lace's Superman. While fighting off waves of hostile attackers. So, actually, it's more like the gaming equivalent of a bad night out in Barnsley.
But enough of my weekend. To save Morplee's planet you have, for some reason, to solve a stack of mini-challenges while shooting down pesky space invaders. For the most part, you'll get a one-word instruction - it's things like copy, shoot and organise here, not ski, sleep sneeze and so on.
The challenges are inventive enough and they'll come in a different order every time - the hardest part is beating the clock, so get your clicking finger limbered up. Play Morplee here.
You are the tiny nation of Qwop's most accomplished athlete, sent to represent its proud people in the field of international running around. The only problem is the training programme wasn't terribly well funded. This is a genuinely hard game to play because of both its controls - two keys control your thighs and two your calves - and the fact you're laughing so hard you miss the starting gun.
Ideally, you're aiming to show Usain Bolt, Asafa Powell and Tyson Gay how it's done by masterfully blazing through 100 metres and into the history books. In reality, my first few distances registered in the minus column thanks to that control system sending my Olympic hero scissor-kicking into an undignified pile on the track. The Chariots of Fire theme had barely even started. But remember, it's the taking part that counts. Play Qwop here.
7Chase Goose 2
NinjaKiwi's Chase Goose 2 is from the Daley Thompson's Decathlon school of keyboard-pounders. Thoroughly old-school down to the Commodore 64-style music, it is, well, a big chase. Our feathery hero has had the tables turned on him and is being pursued by a worm. A very big one. Hitting the left and right keys gets the goose going and you've definitely got the upper hand in terms of speed. Alas, this isn't a flat sprint. And you can't fly. But then it wouldn't be a hard game.
Jumping various holes in the ground requires you to hit a particular key - or as you progress, to do some quick mental gymnastics to answer little questions. To complicate things further, you'll be asked to hold down other keys while still skipping across the keyboards and generally tying yourself up in knots.
And all the while, that worm stalks you, relentless and merciless, like a Boris Karloff monster. Sort of. Play Chase Goose 2 here.
8The Scary Maze
Abandon hope all ye without a steady mouse hand. This reworking of the fairground favourite where you have to pass a metal hoop along a twisted wire isn't especially scary given its title - but it is extremely hard, which is good enough for this list.
It's all plain sailing early on, with a generous inverted L-shape to get your started, but the mazes become tougher and tougher - and beware, there's no time-outs or breaks here. Once you complete one level, you're straight into the next one, so even a momentary lapse of concentration will send you, despairing, back to square one. Play The Scary Maze here.
9For the Twin
Ever needed to pick out a shapeless, alien form from a line-up of similar looking shapeless, alien forms? No? Well here's your chance. For the Twin from Hybrid Mind Studios is high on cutesy charm and the wobbly, hand-drawn style animation certainly adds another layer of trickiness to picking out the matching chap for the mugshot you've been given.
The difficulty level is cranked up with each new challenge, adding changing backgrounds, perspective and movement to your list of headaches. On the plus side, everyone smiles and jumps when you get it right, which is nice. Play For the Twin here.
DiscipleOfFred are back with more games within games in the retrotastic Tail. You control two glowing, Tron-like cables (or tails), one heading north, the other going south. The trick is to avoid the nasty red glowing thingies and to pick up the altogether more agreeable green glowing thingies. There's the occasional purple glowing thing too, which may be medals, but I'm not sure.
The element of rub-your-tummy, pat-your-head in trying to grab one set of blobs while avoiding the other certainly makes Tail a tricky customer - although the hardest thing about this game might be getting through it while listening to that throbbing Europop soundtrack. Play Tail here.
If you think you have found some online games that are even harder than these, then please tell us all about them in the comments section below.