If you asked an average person what they though Hatris was, they would probably (and understandably) look at you like you'd just escaped from somewhere with matresses on the walls. However, if you asked a geek what they thought Hatris was, they would be fairly likely to say "I dunno, Tetris with hats?" And you know what? They'd be spot on.
Okay, so maybe that geek crack was a little wide of the mark: in truth, an awful lot of people have played Tetris. Tetris has sold over 100 million copies... for cell phones alone. That is a truly astounding figure, and one that I struggle to get my head around in much the same way as I have trouble imagining how long ago the dinosaurs lived. But I'm not talking about Tetris today, I'm talking about it's unpopular cousin Hatris. 
Hatris was designed in 1989 by Alexey Pajitnov, probably the world's greatest ever one-hit wonder, the man who invented Tetris and caused millions of cases of carpal tunnel syndrome, along with a man called Vladimir Pokhilko (more on him later). The basic concept is very simple. A pair of hats fall inexorably downward toward their rather grisly destination: a row of severed human heads. This is the kind of gratuitous violence in videogames that is turning out children into killers! The heads actually seem quite contented, perhaps enjoying the simple life where their only worry is whether or not the next hat will be a bowler or a crown. Yes, a row of severed, lobotomised heads, grinning dimly as the drool trickles from their slack lips... sorry, I went a bit off-piste there. So, the hats fall down in pairs and land on the heads. The object of the game is to stack up five of the same hat in a row, upon which the hats disappear and you are rewarded with points. Reach the top of the screen and, like Tetris, it's game over. Of course, there are added complications: for one thing, the hats all stack up differently due to their disparate shapes. For example, if you put a top hat on top of another top hat, they snugly fit inside each other, like a kitten in a pint glass, so that the end result is only fractionally taller than one top hat. However, try to put a bowler on top of a pointy wizard's hat, and the bowler will just perch on top, taking up a lot of space. The hats fall quicker as progress, and as you get further in, more types of hat are added until you've got more types of hat than severed heads to balance them on. 
It really is a surreal, nightmarish vision of hat manufacture, which I'm sure is very dull in real life. Maybe it's a Russian thing. Fortunately, on hand to help you in your mad hat-stacking quest are two hat-factory workers called Alexey and Vladimir (who are presumably representations of Pajitnov and Pokhilko) who you can call upon to help you when you have removed a certain number of hat-stacks. Alexey can remove up to five hats from the bottom of the piles and is by far the more useful of the two, while Vladimir swaps the position of any two of the stack. Seeing the little pixellated Vladimir down there amongst the severed heads has had a strange resonance since I learned that in 1998 he killed his wife and son and then commited suicide, leaving a rather haunting suicide note. A sad ending for someone who helped, if only in a small way, to bring a lot of happiness and sore thumbs to Game Boy owners everywhere.Hatris is not nearly as good as its more illustrious cousin; the gameplay, while fun, is extremely basic and it just doesn't have that same "Just one more go" feeling that Tetris produces in buckets. The music isn't nearly as catchy either, although it is good and features surprisingly little repetition. It's a solid puzzle game, though, and worth playing if only to have the opportunity to explain the madness of the "hats falling onto severed heads" concept to someone afterwards. Speaking of severed heads, they change as you progress through the levels. There are some normal-enough human heads, there's a Frankenstein's Monster head and a vampire head, and then there are these two heads, who may belong to someone a little more famous:
President Ronnie Reagan, I'm almost certain. 
Adolf Hitler or Charlie Chaplin? I'll let you decide. The answer may well say a lot about your mental state.Hatris is, in a nutshell, inferior to Tetris. But then what isn't? Despite being over twenty-five years old, Tetris has yet to be surpassed by any puzzle game. That doesn't mean Hatris isn't worth playing, though. It's a simple enough time-waster that would keep you entertained for the duration of a shirt-to-medium coach journey, and what more could you really ask for? Well, that's all for Hatris. Aren't you glad I got all the way through this article without making a "In Soviet Russia, hat wears you!" joke?